Hey T,
This looks pretty legit. Personally #4,5,7,10 seem the most interesting. From all the pictures I've seen, Iceland is a beautiful country. It would be a shame not to do some hiking or something (unless you just are not into that). The hot springs seems kind of boring imo and more like a "lol tourists will pay us money to go sit in water" kind of thing. I suppose the same could be said of hiking, though :P
The glacier walk seems interesting to me because 1) nature and 2) I've never seen a glacier in person. Westman Islands could also be potentially interesting for the same reasons as hiking etc. I put #10 on there because I like fishing. Look through the list, see what you might enjoy.
From
here #5,6,7 look nice. I'm pretty sure 5 (the perlan) and 7 (the church) are free. Good for pictures and stuff. Also seeing crazy architecture with the church and all that. There are also many free museums including the art museum.
Unless an icelanderman shows up to tell you some specific thing to do, all I've done is ask google "list of things to do in iceland". Similar searches can probably get you a pretty good trip itinerary. Be sure to leave some empty time in though (or include something you wouldn't mind skipping) in case you find out about something more local and non-internetized that looks like fun when you get there.