I'll try to provide a consolidated set of answers to the questions raised:
1. Both of those styles are gorgeous - in fact those are both on my short-list of human hair wigs too.
2. I believe the look of
good human hair wigs is far superior to synthetic, it's just more natural looking and less shiny / nylon looking. That said, your mileage may vary. I'd also take a good synthetic haired wig over a cheaper looking human haired wig any day. The key is too actually look at the item in question and compare it with other tangible items.
3. Good human haired wigs are expensive. Whether they're of value to you depends on how much money you have and whether it comes at the expense of laser, HRT or other parts of your transition. I feel having natural looking hair is pretty high on the priorities but if it meant delaying HRT perhaps it would be better not purchasing a new wig and instead growing out your hair and starting HRT sooner (for example).
4. Synthetic refers to the hair filament type (synthetic as opposed to human hair). Lace refers to the cap construction. I have a lace front wig and it allows strands of hair to be anchored to the front of the wig without the wig cap being noticeable or identifiable. If money permits I think you'd absolutely want a lace front wig.
5. I wouldn't spend money on a wig without trying it on. Certain styles that you think would work for you often don't or don't fit. I'd absolutely recommend you visit a wig shop. You'll pay slightly more than online but it'll be worth it.
6. As a rule, human hair wigs can be heated and styled, synthetic cannot. That said Jon Renau have just released their new HD (Head Defiant) synthetic hair wig range that can tolerate a bit of heat:
http://www.jonrenau.com/wigs/hd-collection7. I have no experience with hair extensions
good luck with that.
8. Cindy's advice is great. I thoroughly concur.