I've just finished fiberglassing my Petrel. I notice that there are a lot of questions on this forum on fiberglassing and about resins. Here are some resources and FAQ's.
The MAS web site is at:
http://www.masepoxies.com/index.html
This is a good FAQ on several general epoxy issues:
http://www.masepoxies.com/Epoxy_School_/Tech_Support_FAQ.html
Here's a video on the MAS product line:
http://www.masepoxies.com/Videos/Introduction_to_MAS_Epoxies___ShipShape_TV.html
This is where you can find info on fillers and filets:
http://www.masepoxies.com/How_To/Tips___Techniques_for_Filler_Use___Selection.html
http://www.masepoxies.com/Videos/Make_gorgeous_fillets_and_smooth_fairings.html
One of the most important things to know is that curing times for MAS slow hardened resin stretch out as the temperature drops. Curing time at 95 deg F is 2.5 days. At 77 deg F it's 5 days. At 59 deg F it's 10 days. There's a chart that shows pot life, thin film set and full cure times that's very helpful. Remember that this is the average temperature in your shop including night time.
I was looking for info and found another good FAQ on the U.S. Composits web site:
http://www.uscomposites.com/faq_epoxy.html
Of interest here is they mention that it's a good idea to shake up hardener before use if it's been sitting around for a month or two. I don't know if this applies to MAS hardener, but it can't hurt. If you're like me, you buy a kit, spend several months on woodworking and your resin and hardener sit off to one side.