How to fry big potato pancakes for hungarian pancakes?
The secret is to use non-stick frying pans. I love cast iron and stainless steel, however when it comes to eggs or potatoes I tend to fall back on the inexpensive, teflon-coated aluminum frying pan because of the very issues you've described. They also require less oil for cooking, so less chance of getting hot oil on you. 

You need the pan to be hot enough at the beginning when you pour the batter on, otherwise the pan will cool too much and the batter will adhere rather than forming a crust, then no matter what you do the result won't be good. Small pancakes won't cool the pan as much which may be why they come out better. I would try putting the pan on as hot a heat as possible (use an oil with a high smoke point like corn or sunflower) and get it smoking hot before you pour the batter on. Then keep it high for a minute, maybe two before turning it down. This should form a crust while on the highest heat, and turning it down will prevent it from burning. As for how much to turn it down and how soon depends on your stove, pans, and batter so some trial and error will be in order. 

As for flipping technique, I would flip it using the whole pan, using the spatula to guide it a bit. It takes a bit of practice but it really is the simplest way. You could use a two-pan technique as you mentioned, you'd want to get an identically sized pan up to temperature, invert it over the cooking pan, then flip the whole assembly over. Any spare oils is a worry as you say, but if you are using non-stick you don't need that much oil so chances are it will be ok. The trouble is you can't have much oil on the fresh pan as you are turning it over. 

No matter the technique you use the most important thing is to make sure the pancake is free to move. You do this by working the spatula around the pancake until the whole pancake slides around. Once it slides freely you can flip it without worrying about it sticking.