I dont think vacuum process is essential, but defo a good idea for a better quality product = and not that hard really - you just need different kit (it's actaually a lot less messy in the literal sense).
The following link gives the concept, but makes it look a bit complicated - doesn't need to be.
NETCOMPOSITES | Guide To Composites | Vacuum Bagging
You can use a hoover for the vacuum, but dont suck directly, you need a pot in betwen to drain any excess resin.
You may want to look into resin additives to give more flexure.
most resin will be waterproof over the life of the blade, epoxy or vinylester is better and have better mechanical properties than polyester, but you pays your money...
