For a 10 gallon batch, my 15.5 gallon keggle is barely big enough for a typical brew. For a 5 gallon batch, I'd suggest getting a 10 gallon pot.
A keggle = a normal Half-barrel sanke keg (15.5 gallons) that has been converted to a kettle. These are made of stainless steel. Stainless Steel is the preferred metal for all things homebrew but Alumnimum is sufficient for kettles as well-- just make sure you boil some hot water in it beforehand to get rid of the metal taste it can impart on your brew.
Turkey Fryer burners are very popular. Be sure to get the square burners for keggles or the base won't be large enough to support the keggle.
As for general tips: I buy everything so that I don't have to upgrade it again...boil kettles are a great example. Eventually you'll want to do a 10 gallon batches (after my 4th all grain batch, I haven't gone back to 5 gallon batches) or high gravity 5 gallon batches where you'll have to evaporate off (like orfy was saying above). So I'd suggest buying a 15 gallon pot or converting a keg to accommodate this soon-to-be upgrade. In other words, try to forsee your future and buy with that in mind-- it can save you a lot of money in the long run.
If you have any other questions, feel free to PM me!
1. BCS - Wet Hopped West Coast Blaster
2. CYBI - Gordon's IPA Clone
3. BCS - Scottish -80
4. BCS - Specialty Saison (Gold Medal at BMO)
1. BCS - Janet's Brown Ale (Fermenting)