Very pleased to be of help
Not that you couldn't have a few fry in your tank, but good to know you went the all male rout. A bit more colorful and less fish to take care of in the long run
xD I don't blame you, a couple Gouramis offered to me as a B-day present I wouldn't be able to say no either, very fond of the species
Looks like yo have what I had that was the wholly terror of my tank, Blue Gourami. The other is a Golden Gourami, had a female once and she was pretty sweet
A good way to tell males from females would be the fins, if their pointed they're males and of they are more rounded they're females. How big are they?
Googling is always good, I like the google machine
Now, to answer your other questions....
I'd add a few more tiger barbs as they enjoy a school and the more you have the less chance of fin nipping from my understanding. I think a minimum if 5-6 is usually recommended? If you want more variety, there are also the green and albinos(my personal fav).
I don't know too much about filters, my knowledge in the technical area of fish keeping is very limited so someone else should answer that one xD. It sounds like you'd be okay though...
Yes, a test kit is a definite must. Knowing the levels of your tank is
very important and being able to test at a moments notice is also important. You should test with every water change and preform water changes with a gravel syphon. BUT get the API master liquid test kit, NOT paper strips as they are horribly inaccurate. It may be a little more pricy up front, but in the long run this will save you money and the lives of your fish even. I speak from experience
Again, your welcome and I'm happy to help
Feel free to ask as many more questions as you like and I'll do my best to answer. Its good to know that your doing your research and asking questions, I wish I hadn't been to lazy two years ago at the beginning to do it xD