How to get rid of as much oil from the schnitzel after deep-frying it

For pan frying you probably want to start with a firm tofu. It's a good idea to press the tofu to remove excess water: wrap the tofu in a cloth and place it between two cutting boards, weighting the top cutting board with a heavy book or other similar object. Wait at least twenty minutes (you can prepare the rest of the vegetables/onions for the stir fry at this point.

Once the tofu has been pressed, cut it into the desired pieces. It's a good idea to fry it at medium-high heat in only oil first, then add sauces (soy sauce, vinegar, whatever) only after the tofu begins to brown slightly.

Note: the above won't simulate deep-fried tofu. For deep fried tofu, you may want to use a softer tofu, still press it before using, and coat the cubes in corn starch before frying. Of course you probably know you can deep-fry at home with just a large pot of oil.

For a different texture you can freeze the tofu before frying.

Although not fried, I would also recommend that you try baked (marinaded) tofu to see if you like that texture/flavor better. You would still want to press the tofu, then slice it rather thinly. You can reapply the marinade during baking for more flavor.

I agree with hobodave that you're overcooking the prawns. But, I would cook the veggies first and then let the prawns cook with them for the last 2 minutes of the veggie cooking time.

One other thing I would suggest is to cut out the salting/marinade stage. The salt could be "cooking" the prawns and is most likely sucking some moisture out.

You could also try reducing the amount of oil you're using, 1 tbs in a pan should be sufficient.