Well congratulations on the gift. Here's my dealings/experience (never owned one before - have had mine a couple of weeks - used constantly).
Short answer: These issues have not bothered me. I actually read more fiction now than before I got the 700 (mainly non-fiction/educational prior) - because I enjoy it more.
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Dust particles under the screen - Haven't had this problem.
Screen contrast lacking when compared to the 505/other devices (due to the touchscreen) - the screen is overall duller than the 505; however, for me, it's not a deal breaker. I haven't encountered any lighting situation that could not be easily overcome by a tilt or turning on the LED lights. Not to be too revealing, but I've used mine in the bathroom; outside at various points of the day; restaurants; before bed; so on and so forth - and haven't thought about returning it.
The touchscreen only being useful if you're using the stylus - generally speaking I don't use the stylus at all. For highlighting text sized at small - I would recommend it - but, on medium, a light drag with a finger works for me in most cases. For turning pages with the touchscreen - I use my thumb (only a small motion needed). And, I use the keyboard the way most use the QWERTYs on their mobiles (two thumbs). And, navigating the menu - I'm all thumbs. Basically, if it isn't highlighting a passage that I can't do with my finger - the stylus never leaves its holster. (People were probably more concerned with smudges - stick to the edges of the screen for page turning, and wash your hands.)
Screen glare - see contrast above. I would say the reflection is more annoying than true glare.
Sony being a bit iffy on the support side of things - no experience thus far.
Lack of mobi support - no problem thus far.
The lack of any open inkpot/hacked firmware/dev/etc - hacking it would void warranty, which would make iffy support a moot point.
I'm not too interested in hacking the device itself but, the books are fun to play with.
I would say that your comic experience would be very lacking. The format of a comic is too large for the screen. So, cross-over panels and the like wouldn't be quite the same. Needless to say - no color.
J