The wind blowing the pilot light out would not cause water to be
released from the relief valve. One big question here is how old is
the unit? If it's older than 10 years, and depending on where it's
located, I wouldn't even fool around with it. Somewhere around 13
years or so is the typical life expectancy. And if it's located where
if it suddenly starts leaking, it's going to do big damage, I'd just
replace it.

As for the tankless, one big consideration in an apartment is whether
you have a gas line large enough to support it. If you don't, you may
not be able to install it at all, unless the building allows the work
and your willing to pay for it.