there isn't going to be a pc version of destiny, maybe destiny 2 but such a multiplayer, loot driven game has to be pretty wary of pc release since you will have to deploy considerable assets to fight hacking and code exploits. I wouldn't be surprised if there is never a pc port of destiny to be honest, they get good marketing money from sony for making PS4 the premium platform for it (bundles, featured on the PSN store, exclusive strikes/gear, etc) and no doubt sony and microsoft will fight hard for the same for destiny 2.
re: infusions, if your item is within 5 levels it will get the new max level. ie take a 295 item, if the lower item is 290 it will become 295. 289 however will turn into 293 or 294. So a good thing to do is find a purple armor piece you really like, regardless of item level, and slowly infuse it up multiple times. Thats why keep all your blue armor within certain ranges, especially for alts, once everyone is beyond a tier then you can just disenchant everything but until then save stuff for infusing.
Also if you do the vanguard quest line that starts with do 5 strikes, then 5 heroic strikes, then finally a nightfall you get a 300 shotgun. Can do it on 3 chars and have 3 300 weapons to infuse other weps.
also had a new icon in my weekly/daily menu, it was zone control and gave +10 marks. seperate from daily pvp, dunno if its a weekly button or daily or if it unlocked cuz i did something