even if it's an M3 tap going through it should be fine (sets usually go down to around the M2 mark). Or you would probably be able to pick up a cheap tap on ebay.

I should have quantified the drill bit statement. On sheet, cobalt drills will be fine, however when it comes to thicker sections you're best using HSS bits (a wee tip for the future there). I can't remember the exact reasoning but it was advice from a very reliable source on the subject of machining titanium.

If my memory serves me right, grade 4 should be bendable to a certain point. Grade 5 and upwards are the ones that are more likely to snap although don't quote me on that one!