Help with set up

so me and my buddy are going to try and get out setup for doing all grain. were going to get a 15.5 gal keg from his father in law. were going to turn that into our mash tun. we just need to make the hole and get the fittings. then we were thinking about doing the 5gal cooler and using that as our sparge water tank. so whats the best way to cut a hole in the keg and were is the best place to get all of the fittings.

You might want to use the keg for a kettle and get a 12-15 gallon cooler for a mashtun, instead. Fittings can be bought from our host.

I guess that would make more sense now that i think about it

There are lots of videos on youtube for converting kegs. There are lots of weldless bulkhead fittings for sale if you do a search. The half barrel keg will make a great kettle and a cooler would make a great mash tun.

+2 for using a cooler for you MT and converting the keg for your kettle. Its very simple to build a jig for a angle grinder to cut the top out of the keg.
But, I have found several other sources to be cheaper on the fittings than our host. And you can usually find 1/2" SS ball valves for pretty cheap on ebay.

As a boil kettle I say go for it. As a mashtun I second, third and fourth what everyone else has said, just get a big cooler. Make sure it is a twelve gallon or more so you can fit big beers in it, that was the problem we ran into.
For the 1/2" hole for the ball valve you can use a step bit for your drill but they are a bit expensive if you want a nicer one that will get the job done so factor that into your pricing.

Keg for kettle and cooler for MLT.

yea i think imma go with that sounds more reasonable.