I use Dial-A-Buoy quite a bit before i go out when i don't have computer access. Obviously you have to be within cell range.
NDBC - Dial-A-Buoy
I keep a laminated sheet with instructions and buoy ID on board so i can check conditions when i'm out for long periods. As you know, conditions can change rapidly if the weather shifts.
National Data Buoy Center
I also use Weatherforyou.com and sailflow
Buoy Center - Buoy Map
As far as what is to much? You'll have to figure that one out on your own.
Depends, IE, Type of boat, Size, experience, Duration you will be in it, skill level, what will it be like when you come into port?
At some point you will discover your limit and/or your boats limit if you challenge yourself. You may not want to go there.
I enjoy heavy weather sailing (my wife loves it, scary) but, i do it in short spurts. Not for days. It will definitely sharpen your skills, especially when things break.
I'm stuck on Lake Ontario for now. It's some of the roughest water i've seen. 10 ft with a close freq can really be a long day if you are caught out (i feared for the boat that day, not mine, 34' C&C). We had the coast guard get rolled twice in 12-14 ft waves. Put three of them in the hospital. I had talked to the Chief PO after. They had one engine go out.
Watertown Daily Times | 5 US Coast Guardsmen hurt during Lake Ontario training