1. If you are thinking 2-5 years down the road for an unknown use of miles/points, having spending on both and points on both will give you more options down the road. It is not diluting but diversifying.

2. chase saph/pref, chase freedom, ink bold/classic; i think that is all of them.

It is hard without a specific goal BUT great that you are doing it now. Miles are only good if you will use them which is why earning miles on the airline that more than likely will either carry you on that special trip down the road or carry you to visit your parents is important or that you will use for work is a good idea. Redeeming for flights usually is better than for hotel stays for most programs (there are exceptions) so I would think earning miles for future trips when choosing between a hotel card and an airline card or general points program is best. You can still have a card that you use when booking at a certain hotel.
Also, life and plans change. Who knows, maybe 4 years down the road you will be posting about using your points/miles for a honeymoon or surprise trip for your parents.