1. Mostly aiming a shot with sidespin will be easier, you can aim it like a center ball shot. If any adjustment is needed it's pretty small. It almost takes one factor out of the equation when aiming. You only adjust for throw.
Playing devil's advocate, if you have spent 20 or 30 years aiming certain shots to account for deflection, you will have to unlearn that and learn the new aiming lines.
2. Some swear yes including one pro I've overheard. My own experience is... maybe? But it's hard to say. Did I really just see the ball spin 20% more, or was it my imagination? Did I just hit it particularly well? I don't know. But, think of it this way. If you get less deflection then you can comfortably cue a bit further out on the ball than usual. Adding extra spin is no problem for the times you really need it.
3. Only you can answer this. It depends on what you're used to already. Mine feels fine, nothing weird about it.
4. At least, say, 3 weeks. Probably a month or more.
5. There's for real, you will realize it after you miss your third or fourth routine sidespin shot =P But honestly I wouldn't expect your game to improve. I don't know that anyone's game truly improves just from equipment unless they were using something with major flaws before, like a fiberglass stick that chafed or a cheap tip that always miscued during draw.
The theory is, for the first few weeks you'll be adjusting and probably miss more and mess up shape. After you learn the adjustment you can aim the tough shots a little more easily (But you must still have the skill and focus to make them). After many months of use, you might be ... I dunno, 5% better at shotmaking with shots that involve sidespin? And if the theory on increased english is true, you can get more action with less force/aiming effort/tip offset, allowing you to play position more effectively.
------
Overall I'd say... go for it if you're definitely thinking of buying a new shaft, and your current shaft is nothing special and didn't really cost you anything. If you're gonna spend 100 bucks anyway on a new shaft, why not just spend 200 and know you've got one of the best? I doubt you'll buy it and be like "man, this is so different, I hate it."