I have a very inexpensive 8 gallon SS hot liquor tank with a sight glass. I also have a 10 gallon plastic cooler with a false bottom I use for my mash tun. My boil kettle is a 15 gallon SS high quality PolarWare kettle.
The main mistake I made when designing my system was my hot liquor tank is too small. I should be using a 10 gallon kettle.
So, my suggestion is to put some thought into how you want your system laid out. Draw some sketches if necessary. This will bring you closer to understanding exactly what you need. For example, my system is a gravity flow system until after the boil kettle. So, this means my HLT is very high - too high to see in side. So, a sight glass was needed. Also, since my boil kettle was low in the system, a pump would be needed to move the wort to the fermenter through my plate cooler.
Also, I highly recommend using induction burners where you can. Their clean, fast and efficient. Propane and natural gas are also great, but special care needs to be taken if used indoors.
I hope this information helps. Good luck and welcome to the hobby!!