I own a 7500 hybrid with a lock-out capable suspension fork so all I can say on that is that it is WAY easier to go on the roads (especially hills) with the forks locked...no surprise there. I say go for it on the forks, a quick search on ebay and google shows a ton of nice looking cro-mo forks for under $100. I can't advise on the quality of one or the other but the investment isn't so high as to result in too much buyer's remorse.

As for the tires, I switched out the 700x35's that came with mine to those exact same Panaracer Pasela's and the difference was noticeable and worth more than the $21 a tire I spent t my local LBS. Bike handles a it quicker, moves a bit faster. Not that it made it into a racing machine, these are 25-30lb bikes after all, but they do fit onto the stock Bontrager rims and they do make a marked improvement. You give up a bit in comfort, once again no surprise there, but you make up for it a bit in speed/handling.

Hope this info helps.