Just closed on my first rental! Newbie questions

[David Gordon]

Hello all,

long time listener of the podcast and searcher of the forums. 

I just recently purchased my first property (an up/down duplex) and I'm excited to apply some of what I've learned through these channels. 

here's a rundown of the property followed by a few newbie questions:

purchased for 95k @ 25% down, and negotiated a $5000 credit via check at closing for deferred maintenance items found in the inspection. The downstairs is 2bd 1ba, is currently empty and will require paint, carpet in 1 room, and a facelift in the kitchen. I expect rents to be 700-750 for this unit based on the market here. Upstairs 1bd 1ba is rented at $520 (market ~$600) but the tenant has been there for 4 years and his lease is through Aug 2020. 

so, my questions:

-upstairs tenant has full use of the 2 car garage on the property. This is not stated anywhere in the lease and it appears it was a handshake deal. I would prefer to offer this garage with the 2bd unit, as it offers the only off-street parking. Am I stuck allowing use of this until his lease is up? I understand I have to honor existing lease, it is not stated as a part of any terms. 

- I understand the lease conveys with the property, but shouldn't i create my own lease (without changing existing terms) for the duration of the current lease? What, if anything, can I change?

-rent payment: tenant has deposited cash into previous owners bank account to pay rent monthly. My bank is uncomfortable with this, as am I. I have set up a cozy account and discussed it with the tenant, who seems apprehensive. Any advice on making the switch? I would much prefer to do it online, and the lease basically states "any means acceptable by landlord", so it's vague. Can I require online payment? 

Finally, is there any advice you'd offer someone just getting started that you wish you knew at the beginning?  

Thank you, and I hope to be able to contribute as I learn along the way.