To summarize the above:

Basic print exposure and contrast determination is as follows:

1. Make a test strip to find a basic print exposure based on highlight values.
2. Make a test print and evaluate contrast. If you need to change contrast grades, then start over at number 1 If not, continue with 3.
3. Have fun determining and executing your print manipulations on the way to making a fine exhibition print.

You will find that when changing contrast it will save you a lot of time and paper to just start over with a new test strip. The so-called "speed-matched" filters are calibrated on a low-middle grey, not a highlight value, which you are (and should be) using to determine basic print exposure.

It is best if your contrast filters are flawless. It's worth getting your own set and carrying them with you in and out of the darkroom if you have any issues with the filters that are available there. That said, filters that go between the light source and negative are usually more forgiving of dirt/dust/scratches. If the filter is anywhere below the negative, it can't be clean enough.

Using a longer enlarging lens than usual for a particular format will result in the distance between enlarging head and paper being greater for any given size of print. If that's not a problem for you, and the quality of lenses are equal, then there is no difference in print quality or printing procedures.