I have a hard time with my hands in spraying all my plants and veggies. Is it ok to use the "drench" method at same diluted rate as the spray, rather than spraying, or is the foliar method the best way?

There are a certain amount of nutrients and benefits of those that the plants can take up foliarly. But, drenching would be better than nothing. You may up the formula a little but I think it is about the same. With some of the urea based products, you have to cut back so as not to burn foliage. But with GJ I don't think there is a need to cut back or increase.

What kind of sprayer do you use? Have you tried a trombone or pump up sprayer ?

I use some plastic jugs from the garden center. Have to squeeze the things to spray. I have some old pump up type from long ago when used to kill weeds, etc. Don't want to use them because of maybe resideue left in them.

I bought a package of spray bottles at Target that I use for organic sprays with no worry of residue. Or you can just go buy another pump sprayer and mark it for organics only.

I use a simple small cup or small plastic bottle with a 5 gallon bucket, everything I use my aerated compost tea recipes as a foliar and soil drench application on all my crops and ornamentals.