What I am trying to figure out is if I should continue making repairs and attempt to make it cashflow positive or fix it up to sell.Current Issues: Leak in basement and retaining wall by the driveway that need repair.Minor Issues: Water pooling in backyard, deck could use work (functional, but not pretty)Has anyone had any similar problems?

You're talking putting houses under contract without ever personally seeing them (trusting some pictures or someone elses word) then attempting to present that product to someone else to buy.

I am currently in the process of attempting to purchase a quadruplex, with 3 tenants currently living in and paying rent.

I'm in Denver, where you don't even have to remove the dead bodies and you still get top dollar for it.

I attempted to partition it into two APNs so that in the future I could sell one, hold the other to another year and thus spread  the tax hit. 

I hope the deposit can be $10k or less and to use the rest for rehabbing and buffer.I have a good job with a good salary, so, if things go south a bit, I can cover a bit of the payments with my salary.My plan after that would be to attempt once again to get a lender in the US to lend me money on my two properties, one which I don't have any mortgage on, and the other which I would be essentially refinancing, and from there, buy my third.I'm sure after my third, some of the potential investors I'm talking to will be more interested in my business.Is this plan sound?

Connect with someone doing deals, learn then apply what you learn, do not even attempt this just yet, it will not end well.

Since you will be making no attempt to re-rent, prorating to the day they move out would be normal.

Try to and you'll get blasted out of the water.When a lease attempts to address every little issue, you'll likely be found as being unreasonable and allowing the tenant the right of quiet enjoyment, you shoot yourself in the foot again.If you rely on a college student base, you'll get a reputation and the kids (if not the college) will black ball you, you'll get a bad reputation for being whatever.

Per the tenants, the previous owner attempted to resolve this issue before.