Your 1/16 electrode ought to be ok up to 100-120 amps (assuming your torch is water-cooled), however, a 3/32 electrode is not a problem if you find it performs better. My advice is to examine some production Titanium welds, many people are surprised to find that it does take considerable current to get the weld profile required. The typical weld profile for Titanium groove welds at the thickness you suggested (0.090) may be slightly wider than that of stainless of equal thickness. This is not a worry as long as you have suitable argon trailer coverage as the weld cools behind the puddle.

The technique of welding over the filler wire without dipping can be fine as long as you provide sufficient heat to get complete fusion. Insufficient heat input with this technique will result in LOF. With the amperage required to weld your pipe I don't see a problem with dipping your wire (titanium stickyness is much less of a problem with groove welds at high heat inputs). Just make sure your filler input technique is correct, this means keeping your filler tip under the argon envelope at all times. If the wire exposed to the atmosphere stop and clip the end.

If possible I would stick to the beveled end prep with little or no gap if possible in order to minimize possible atmospheric contamination.

tell us how your trials proceed