Well, this might lead you to a range of things you
need! It sounds like you've already got the boil kettle, so at the very least you'll need an MLT (mash-lauter tun, something to mash your grains in), but you can definitely go crazy and start adding pumps, tiers, etc. A lot of people use the coolers, and the DIY section has a bunch of examples. Here's the one I was able to find
quickly off-hand. It is probably too small for your batches, but here's a nice
table to let you figure out how big you have to go.
You'll also probably want to sparge (rinse) the grains after mashing, so for that you either need another big pot that you can heat water up in, or some sort of container you can drain the wort into after mashing while you heat water up in your boil kettle (even a plastic bucket would work for this).
The other option is Brew-in-a-Bag. Search BIAB and you'll come up with all kinds of posts. Basically you use your boil kettle and you get a bag large enough to fill it, put your grains inside the bag, then when the mash is done you pull the bag out and let it drain above the kettle. Of course for this, you've got to be able to hold a wet, 10gal grain bill or come up with some way to support it!
