I'll throw my 2 c in even if I don't have 2c since I'm a beginner
and only parroting what I read:
There seems to be some controversy here - some say downcut, some say down/upcut
and others say straight/double fluted with bottom flute since it gives
a cleaner cut. I kind of go for the last solution as it's probably cheaper
and maybe you're less likely to break the bit.
Regarding the pressure, you will both hear the router begging for
mercy / fighting and maybe see burn marks if you're too heavy handed.
Just take it easy - there's probably some rough figure on how much
you can take (others will tell you) but I think it depends
also on how powerful your router is and the bit type - do it safely.