"SAC305" and Sn96.5/Ag3/Cu0.5 are the same thing, SAC is just an acronym for Sn/Ag/Cu or Tin/Silver/Copper. The "305" refers to percentages of Ag and Cu (ie 3% and 0.5%). This is really on the only readily available lead free solder in widespread use. SAC105 is also available but offers no real advantage.
All the lead free solders are higher soldering temperature, SAC305 melts at 217C vs SnPb (37% Pb) lead solder at 183.
For hand soldering I prefer wire solder, but paste is possible too. The paste has a shelf life though, after a year it may be too thick to extrude from the syringe.
For fine pitch SMT parts you will want the finest gauge solder.
The key to a good lead free joint is plenty of flux. The fine gauge solder has so little flux in it I always add flux, either liquid from a dropper or "flux pen", or tacky paste which helps hold the parts in place while soldering.
Flux comes in 3 basic types:
No Clean: Requires no cleaning or solvents as the residue is inert. Note that this is invariably the least effective kind of flux in my experience. It is also very difficult to clean should you want to.
Water Soluble: Very strong and produces very irritating fumes when soldering. This must be washed with water to remove to avoid corroding the assembly. And then the assembly must be dried with something like a hair dryer. I avoid this type for hand soldering.
RMA or "Rosin, Mildly Activated" flux. This is the kind I prefer and gives good solder joints w/o noxious fumes. It should be clean off with Isopropyl Alchohol and a brush after.
I would recommend a fan to create a gentle air flow to push the fumes away in any case. Too much air will make it hard to solder due to cooling.
And lastly you need a soldering iron designed to reach the higher lead free temperatures. I always recommend a Metcal with interchangeable tips. They are expensive new, but are built like tanks and older quite functional units can usually be had for less than USD$200 on ebay.