150x write speed should be fine- high speed cards are rarely a problem with modern PDAs and we use them all the time. The iPAQ supports SD but not the new SDHC cards. Cards that are 2 gigs and less are standard SD and those that are 4 gigs and more are SDHC with the exception of a few standard 4 gig SD cards such as Transcend's 4 gig card. There are many good brands of cards out there including ATP, Sandisk, Transcend and more.
For screen protectors, I personally really like the ones from www.pocketpctechs.com. They have a crystal clear one (you really can't tell it's on there) and an anti-glare one (slightly noticable).