If it is stainless steel as the base metal, use a very sharp bit and turn it very slow with lots of lube. Running the bit at normal speeds for plain steel will overheat the bit and the stainless causing it to harden at the hole very quickly.
Just go slow with lube and you'll be okay.
Tapping the hole is the same, reverse your tap frequently and use lots of cutting oil. The tube can't be more than 1/8" thick anyway.
