Questions on my first cider

I "brewed" my first cider a while ago - it has been fermenting for 34 days now, I plan on racking it today or tomorrow to secondary. I recently took a gravity and a taste and it is sitting at 0.997 and tastes pretty harsh. I was prepared for it to not taste fantastic, but I was not prepared for that gravity reading.

First question: Should I be worried about the taste?
Amplifying Info: Fermented at 72F, WLP007 English Dry Ale (helps explain the FG), taste is somewhat medicinal/industrial, possibly fusol alcohol, but I'm not exactly sure what that tastes like. Body is very thin, but still tastes like cider/appley. The juice was Martinelli PURE apple juice - absolutely nothing added, but it is pasteurized.

Second question: Will the following method work for sweetening/carbonating and does anyone have any suggestions on times/amounts/etc. to shoot for?

Method in question: I'd like to add some volume of fresh juice (same type) to my bottling bucket (after a few months of conditioning) as priming sugar and to add body. i did a quick calculation (C1V1=C2V2) and I would need 1.8 gal of my juice (SG=1.055) added to my fermentation to get up to 1.015. I have no idea if that is the correct gravity I'm looking for. Anyway, I would then bottle and let condition/carbonate for some unknown period of time, then pasteurize to stop the fermentation from drying my cider out. I'm guessing I would want a finished product at 1.010, again a guess.

I'd appreciate any insights on trying this method. Thanks!

Update: I ran some numbers, please let me know if these look wrong:

Based on adding 4oz priming sugar/5 gal beer for bottle conditioning, I get that that is about 0.598 Brix. An online conversion tells me that is a SG of 1.002, so I guess that means that your standard bottle carbonation consumes 2 Gravity Points. Therefore, I would want to shoot for 1.012 for priming, then try bottles until they are properly carbonated and they should be at 1.010 and properly sweet. Then, pasteurize.

These numbers are very rough approximations and I know I am calculating this using corn sugar and fructose will behave differently, but I'm not designing the space shuttle here.

what gravity did you expect? any self-respecting yeast will take 1.060 apple juice to below 1.000. i bet that it will improve greatly with time. it only takes one experience with a nasty tasting young cider that you are on the brink of releasing into the sewers that magically transforms into deliciousness to convince you that it stands a good chance of improving greatly.
if you are really sure that you want to sweeten it, then you really need to do this by taste. adding apple juice to sweeten and prime works well. i haven't worked out the numbers myself (and can't be bothered to do so right now) but i really don't think that carbing to a 'normal' level will result in a drop of 5 points, i would get the calculator out for that. for my tastes 1.010 is very sweet but of course it depends a lot on the character of the cider, notably the acidity. i would also recommend bottling a few bottles unsweetened and just primed normally, so you have a dry reference. i always end up liking dry more than sweetened, but that's just my taste.
of course be careful carbing such a sweet cider, open a bottle regularly to test carb level, and for me bottling one or two in plastic soda bottles (after being really sure the priming juice is well mixed in) will let you know when they are in the right ballpark to pasteurize; when they are hard but not rock hard they are to my liking. you don't want exploding bottles, unless you do, in which case you do.

Well, I didn't really have an expected FG, but none of my reading about ciders led me to believe I would get below 1.000. Apparently, I didn't do enough reading. I'm glad to hear that you think the taste will improve with conditioning, I just didn't know if fusol alcohols would mellow out.

I really like a few of your suggestions. I will definitely be bottling some of my cider "as-is", without sweetening. Also, I think that I will do an experiment and prepare samples of different gravities, maybe 1.002, 1.006, 1.010, and see what sweetness I like, and prime accordingly. My favorite thing you suggested was to bottle in some plastic soda bottles so I know when to pasteurize. That is so simplistic it's genius. I should have thought of that.

Regarding the gravity points consumed for priming, on my post above I ran the numbers and I get that standard priming (4 oz priming sugar/5gal beer) equates to 2 gravity points.