I'm going to reply to these questions but I think I have to let you know that, first, I'm pretty sure you're misspelling some things here, I thought you were copying directly from a script in the game files but I guess not; second, I feel this text is way above your level right now, you should start with easier things, and seriously consider reviewing grammar (or relearning it). Also, you shouldn't stop at every little thing you don't understand as that will make things too inconvenient, if you just read a lot of easy stuff and keep climbing from there you'll get a feel for things you don't understand (of course, do look up stuff but I'm saying if you stop at every single doubt you have you'll be going too slowly). Another thing I notice is you seem to be relying too much on understanding Japanese concepts through English, as in trying to directly translate them. For the most part, you should create a blank slate in your mind to learn Japanese in, trying to understand the concepts themselves as if you were a native instead of correlating everything with some English equivalent.覚えていますか？
覚える means to remember (well, it does mean some other things sometimes, like to feel an emotion, but you don't need to worry about that now). The ～ている form doesn't necessarily always mean that something is happening right now
, it can also mean that something is in a certain state. You've surely seen 「知っている」 somewhere, which is just an inflection of 知る but 知っている is used way more often than the base verb, since it means something like "being in a state of knowing". Likewise, 覚えている means "remember". This is probably tricky to understand since in English you use the same word to mean "remembering something constantly, the fact that something is stored in your mind" and is also used to mean "something just floated up to my mind, I recalled something". 覚えている means the first, for the second one you use 思い出す. Also just in cased you missed it, 覚えている becomes 覚えています because it's the polite (keigo) form.Basically, the simple answer to how that translation should be is "Do you remember?".あの日 ふたりで見た
Is this something that comes before the next sentence you posted? Because it's hard to explain like this, and it looks like it'd fit right in with the next thing.They didn't see two people; it says ふたりで
, this means that this action was done through or by the means of ふたり. So this is referring to either the speaker plus another person, or two other unrelated people having seen something together. ふたりで is a very common construction though, so you might as well think of it as its own word.ロトゼタシアの美しさい景色を。
Assuming that you made a misspelling there and it's actually 美しい, it means "[did some action at/to] the beautiful scenery of Rotozetasia(?)". In Japanese you can change the order of things in almost any way you want, so say the previous phrase was actually connected to this one, you'd end up with 「あの日ふたりで見たロトゼタシアの美しい景色を。」("The beautiful scenery of Rotozetasia we saw together that day"). You can swap things around and you end up with 「あの日ロトゼタシアの美しい景色をふたりで見た」("That day we saw the beautiful scenery of Rotozetasia together"). It's the same sentence but with the order changed, to give emphasis to the ロトゼタシアの美しい景色 and/or to sound more poetic.吸い込まれそうなほど 真っ青な空 。
This is probably just a continuation of the above, as well as the following few sentences.～そう is an inflection that means that something "looks like" that action; here this would mean something like "as if swallowed up/looks like it's swallowed up".ほど when attached to verbs in this way means that the thing following is "at the level of" or "like that action could happen", for a lack of a better explanation.This is all applied to 真っ青, which is then in turn applied to 空, so you'd end up with something like "A sky so blue it could swallow you up".夕焼けに染まった 茜色の海。
This is all just embellishing an adjective+noun again. 「夕焼けに染まった」, "painted/tainted in/with the light of the sunset"; 「茜色の海」, "red (I mean I haven't even read that color before so you can make it a fancier word than just 'red' probably) sea/ocean". So obviously you put these 2 together and you get a "red sea painted with the light of the sunset".生命のかがやきに満ちた 大樹の葉。
Same again, just a bunch of adjectives and stuff.You get the first, 「生命のかがやき」, "the shine/brightness/spark/whatever of life", which has 「～に満ちた」 with it. 満ちる means to be filled (like a glass filled with water), so both together mean "filled with the brightness of life".Then you have the other thing, 「大樹の葉」, the leaves of the great tree, so yeah, when you add in the whole previous block you get "The leaves of the great tree filled with the brightness of life".あなたと共に見た そのすべてが
今も 私の心に 焼き付いています。
First you got あなたと共に見た, "saw together with you", coupled with そのすべて, so you end up with "all those things I saw with you". Then が says that all that stuff does something.今も would be something like "even now".私の心に焼き付いています is in a pretty standard order so you should understand it, something like "burned into my heart". So all this together you'd get something like "All those things I saw with you still burn/are etched in my heart"何度読んでも すばらしい文章だ。
キミには せび この手紙の都合続きを
That 都合続き seems pretty odd, like the 都合 would be another word or just shouldn't be there in the first place. Also, the せび is definitely ぜひ. Assuming that the 都合 isn't there and that ぜひ is corrected you get something like "No matter how many times I read it, it's a wonderful text/poem. I want you to look for the rest of this letter."
By the way this is a pretty good site
for searching specific pieces of grammar, but I don't think you should use it to study grammar per se, but to get a better understanding of things you've already seen and aren't understanding very well, or to review things you already know.