On corner steadies spray with aerosol grease, chean first with solvent, allow to dry then spray, white lithium grease probably best. If that don't free them up then thread have had it or they are bent.
I find any cheap blue fluid is ok, if you get 5litres its about £10. The real cheapskates can use cheapest possible value biological washing liquid. Use plain water in top tank, I find theres no need for pink.
1. Things like water pump and display on the fridge are often 12v as are some of the lights, in which case you would need a leisure battery.
2. If the corner steadies are stiff to wind, grease well and wind several times up and down.
3. Sorry I can't help with a local caravan breaker.
4. I use my local caravan dealers 'own brand' toilet chemicals which do the job perfectly. Places like Aldi and Lidl often sell toilet chemicals when they get their camping gear in.
5. My number one caravan gadget has got to be my low wattage Quest hot plate/griddle.
I use oil on the steadies. Grease tends to attract the dirt and turns into a grinding paste.
If the caravan has a 12v regulated output not just a charger then you wont need a battery. But i would always fit a battery. Even if its the smallest/cheapest car one.
Caravan breakers tend to come and go quickly.
I prefer the proper brand of chemicals. Found that you use more of the cheaper ones so not cost effective.
No.1 caravan gadget. The motor mover. Expensive but worth the money.