re: Any negative for having too many CCs open?

A lot of opinions on here are based upon individual credit situations (i.e. this is what I see, I did, and what changed for me).

The reality is that there are about 7-10 credit buckets that people fall into. Different factors affect each bucket differently (i.e. opening up a card, utilization, length of time opened).

What places people into the different buckets?
A lot of things. If you are 18 years old with limited credit history, you are in a particular bucket and your score changes differently than other people.

If you have had installment accounts opened and closed several times, then you are in a different bucket. And what affects you is absolutely different than that 18 year old.

If you have had a mortgage history for 15 years, you could be in a different bucket.

The point being that credit repositories do not apply a 1 size fits all approach to scoring.
They have developed a highly complex system to help anticipate the likelihood that someone could get 90 days past due on one of their accounts. As I said... factors that affect an 18 year old score differently than they would someone in their mid 30s (several installment loans paid as agreed and closed) or someone who has discharged a bankruptcy and is rebuilding credit.

All of the premises for good credit are the same. But the weight that they affect someone could be entirely different based upon the credit bucket that the individual falls into.

I think you have a good grasp of credit. And that you will be fine. If anymore questions pop up, don't hesitate to ask.