I have, on multiple occasions, asked my clients to lower their offer price, and they have gotten into contract on those homes! 

Do I simply need to write it on the purchase contract?

Then you could end the contract if you feel there are extra people there.Of course it is discriminatory to not rent to an applicant for being at the occupancy, so tread softly and document your decisions.We have had occupants at the max, we let them know before they sign that no additional people are allowed under any circumstances. 

Looking for some advice on time usage and how to manage your "today investors" with your "tomorrow investors" all while servicing your "right now contracts".

find a good deal, get it under contract and figure the rest out step by step as needed. you said yourself that you have been thinking about this for a long time. if you are in the mindset that you have to have the complete puzzle solved before you mak your first move you'll be sitting on the sidelines forever.

Expect to pay anywhere between 1-4 points on a deal, depending on the property, experience and loan amount.Do you have a property under contract? 

If they want a premium then they typically will have to wait for a long time under contract so I can get everything approved and have an executed lease with a tenant in hand.I have to know I can get premium rents to be able to afford the land.

The price we are in contract for is right at market value or possibly 2-3% above.

I have used land contracts, foreclosures, and refinancing to grow my portfolio.

I am under contract for my first property.