Hi mate
Great to hear you are going to be doing some track work in your ute.

Here's my 2 cents worth.

1. Tyres - Personally I like using street legal semi slicks so I can have the car ready to go the day before and simply turn up, check the oil and tyre pressures and hit the track. Grab a set of second hand semi's from one of the IPRA boys in your area and then stump up for new ones when you want to chase times. Or for a decent alternative try Kumho KU36 tyres. These aren't a true semi but are way better than a road tyre.

2. Bonnet latch - The cheapest way is to use an old pants belt with one half pop riveted to the underbonnet support panel near the catch and the other half attached to the front bumper bar. Another easy, but dodgy looking way is to use some rope looped around the bumper bar and the bonnet catch.

3. Tow hooks - Currently I am just using the factory front tow hooks and my rear tow bar mount but next week I will be cutting up a spare seat belt and bolting a loop of it at the front and the back. Another way is to use tie down strapping.

4. Triangle - Use a magnetic one if you would rather not draw attention to the car when driving on the street. The alternative is a sticker. The cheap way is to pop into your local news agent and buy some blue contact book cover wrapping or you can buy a specific motorsport sticker (You can buy the triangle individually or as part of a motorsport sticker labeling pack). Both magnetic and sticker versions can be purchased online from race shops.
Headlights - Just make a cross across the headlights using electrical tape at each meet.
Fire extinguisher - Use a metal mounting bracket not a plastic one. Bolt it to the seat frame in front of the passenger's seat.

5. Clubs - no idea sorry mate.

Let me know if what I've said doesn't make sense and I will take some photos tomorrow.
Matty