Advice for Racetrack Videographer

Newtek Tricaster, with remote cameras would do it nicely, although you didn't mention the critical thing – budget.

First there are battery packs all over the internet you can simply plug your cameras into that can power them all day long all over the internet. As for remote controls systems there are remote follow focus etc and remote zoom controls, and remote camera controls all on B&H photo, but it’s more expensive to get remote panning. So maybe just remote camera controls and preset your focus and angles for your budget. Any remote camera controller on B&H or Amazon will do it.

NO! security cameras are optimised for their specific purpose. Mind you, if your quality level is not expected to be very high, and the cameras not panned and titled live, they'll produce images. 

We're usually backwards in the UK, but most of the track racing here gets fed to screens, and is cut live – and security type systems wouldn be acceptable at all – as the production is iffy. Security systems are good for wide angle static images, but as soon as you try to pan/tilt/zoom and focus, they get horrible quickly.

I'd hate using this sort of equipment to record races?

Security cams and systems are designed to record all day which means they use very low bit depth quality footage.

If your clients have no compaints then stick with what you have already hands down. If they do have a complaint then rent what you need and charge them for the rental till you can purchase it. You should be investing in understanding how to build and grow a business through proper marketing before buying g gear you don’t absolutely need. If you constantly invest in gear you’ll end up with a lot of gear and no business. Spend your time learning how to expand and drive sales. Cold calling is something everyone should know how to utilize.