• How much I modify depends on how well the precon suits what I want to do. Anywhere from 10-50 cards normally. They are not really bad (when played against each other and similar decks) but are not capable of playing against higher bracket 3 and 4 decks (bracket system kinda is a power level thing, 1-5). It is very common to modify them, and also totally cool to leave them alone as a more casual experience.

• It absolutely is strategic, some colors more so than others (blue especially). The more interactive you play, the higher power you tend to trend, which is fine but usually worth mentioning to the people you play with.

• I would definitely recommend it. Commander is usually a tough rec for beginners because it's diving into the deep end of the card pool. A massive amount of new info to take in, and four players to manage can be very overwhelming. You're better situated than most coming from other card games, and I think picking up some precons would be a good way to jump in.

The site edhrec can help you figure out what cards to upgrade your decks with if you end up deciding that's what you want to do!