I ride in the south east asian sun and its absolutely brutal even when overcast especially if you are a pale skinned caucasian. In terms of sun cream if you have really fair skin and suffer in the sun this stuff is the absolute daddy. Except no substitute.
http://www.watsons.com.sg/Product-Categ ... p/BP_54200
Regarding sun hats I started out using baseball caps but kept losing them after big wipeouts and getting a sunburnt scalp. I then switched to using the floppy bucket hats with the chin straps. I have a massive noggin and of all the brands I find that the Billabong surf hats fit my enormous mutant Mekon like head the best. If you are a little smaller in the cranial region try the ION hats.
Rashie wise I have tried a few brands but keep coming back to Quiksilver because they seem to last the longest without falling apart and the gorget is a bit lower cut and less constricting than most of the other brands.
Shorts wise if boardies aren't cutting it and you don't fancy lycra 'yoga pants' try the three quarter length Haglof shorts. I have a couple of pairs, they are super comfy, don't weigh a ton when wet or stick to your legs in an annoying fashion when wet.