All Grain upgrade question

I'm looking to upgrade to an all grain setup and have two equipment questions:

I know ideally I'd have two big (~10g) kettles for heating mash/sparge water and for a boiling kettle but I already have a cheap 4g pot that came with my brewing kit. My question is--for single infusion can I get away with just buying one ~10g pot in conjunction with the 4g? I was thinking I'd heat the brewing water in the big pot, mash in, drain into the big pot, and heat the sparge water in the 4g. Does that sound reasonable (at least for the time being)?

Secondly, I know this has been talked about but can I manage this setup without a turkey fryer? I have a big oven, I think around 15,000-1,800 BTU. Don't mind waiting a little longer for things to heat up

Thanks!

As to the first question, I do average gravity AG beers with a 7.5 gallon and 4 gallon pot. I heat my strike water in my 7.5g pot and mash in a 10g cooler mash tun, drain into the 7.5g. I double batch sparge, heating the sparge water in the 4g pot.
I do use a propane burner, so all I can say is to try and boil 6.5-7g on your stove and see if it works

Also, my 7.5g pot is really too small, but it was free.

First question absolutely reasonable. Second question, just spend the 70 bucks on an outdoor burner, it'll speed up your brew day among other benefits.

For the first question, I did just that til my dad bought me a 15 gallon pot. I also use a propane burner, but some people have had luck putting the pot accross 2 burners on the stove. I guess it would mostly depend on the shape of your pot.

I have one 15 gallon pot. I brew 10 gallons every brewday in the manner you detailed. I heat my strike water to mash in temp and then scoop that into the mash tun/cooler. Half way through the mash I begin heating my sparge water. I do a double sparge so the first runnings get collected into a bucket. I then add my second sparge water, then dump my first runnings into the pot and start heating. As it heats up, I dump my second runnings in.

1st Question: Absolutely. That's what I used to do.
2nd Question: Absolutely. I used to brew with an 8 gal and a 4 gal pot on a glass top stove. Takes forever to get your wort to boil, but it works.
Prost!

You can also consider building a heatstick to help your stove out.