Not sure I'd bother with carbide, but I haven't had to drill that many holes with hss. HSS might be easier. I drill hardened stainless (17-4 h900) with coated hss.
Going 20x the diameter isn't optimal. Are all the holes in one part? If not than good, because you're likely to break a bit going so deep.
The problem with running high RPM is that the bit can whip out from the centrifugal force. Of course it depends on how long it is.
Sometimes I slow the rapid down and set the plunge clearance a bit high to give the bit a chance to cool and shed any chips.
You can't blast the coolant or the bit will deflect away. For aluminum, normal coolant should work just fine.
It's hard for me to say how fast to run because I don't drill aluminum and it's one of those things you have to play around with. Every job and machine is different. Maybe your spindle vibrates, maybe your bit is running out, maybe you didn't spot drill very well, maybe your coolant is bad .
You'd be surprised how slow in RPM you can run those tiny bits. You don't have to go mach 5.
In the stainless I might peck around .004 or so. I'd rather stay on the conservative side and get the job done.
I'm always surprised how well the tiny bits do. It's hard to believe they can drill anything.