First, allow me to welcome you to Tropical Fish Keeping forum. Glad you joined us.
Filter. The size rated for the tank is adequate for what you are intending. I would place it at one end, this creates a natural flow down the length of the tank. You want a gentle flow, not a raging current for the fish intended, and I'm not familiar with the specific filter mentioned but there are usually ways of achieving this. The heater should be placed close to the filter return (water entering the tank from the filter) so it will heat the water as it flows past and down the tank.
Plants. i second having live plants. These need not be difficult, if you can maintain healthy fish in a tank there is no reason why live plants will not be successful. And the benefit of plants cannot be understated. Aside from the water stability facet, all forest fish (the species you have so far mentioned are all forest fish) appreciate having plants. On this fake will work almost as well, in that they provide the shade, security, etc., but the benefit to water quality from live plants is something you should not ignore. Fine gravel or sand will work. If you have not already decided on the substrate, we can discuss this further, as there are some that are better than others not only for plants but fish (esp substrate fish). It would also help to know your lighting.
Fish. Other members have noted some issues, i second those. If angelfish are to be the focus, a group of 5 or 6 in a 75g would be lovely. Sword plants (Echinodorus species) suit this fish admirably, along with some floating plants.
As for tankmates, these have to be carefully chosen. Angelfish are slow, sedate cruisers, and they have very long fins. Most barbs will nip them. Some danio and characins (tetra) will too. Plus, you want slow sedate shoaling fish to work well with angelfish, no boisterous active swimmers as this can annoy the angels and that means stress. And stress weakens the immune system, result is unhealthy fish. Some suggestions are included in the profile, click the shaded name Scalare Angelfish.
The "sharks" are not recommended with slow fish. They can get nasty as they mature, and one of either species means no other substrate fish, which is a shame, as a 75g tank has lots of space for some interesting substrate fish like any of the corys, Whiptail catfish, bristlenose pleco, etc. These are in our profiles too, click the names.