Looking at buying investment property - Residential across the street - Need advice

[Sean Weddingfeld]

Been listening to the podcast for over a year, and this is my first post. I might have a good opportunity to finally pull the trigger on. 

My wife and I have been at the same house in northwest Denver area (Arvada) and have been there about 15.5 years. We bought it for $270k, have $145k left on the mortgage, and it is valued at about $690k.
Our old neighbors across the street, bought that house in 2019, moved out of it a couple years ago, have been renting it since then, but are now selling it for $880k. We are looking at buying it and being able to turn it into a mid-term rental splitting the top and bottom levels, for two rentals, and furnishing them both. It is a 3,300 sf ranch style home on a smaller lot so the outside maintenance is manageable for me living across the street. Top level is 3 bed/2 bath, bottom is 2 bed 1 bath. Looks like we would be able to get $3,000 for the top and $2,000 for the basement, conservatively. Likely be able to get a $200-$400 more per each on those in reality. Probably need about $10k for the conversion to two units, and $5k to furnish each level.
I have been looking at getting back into having a rental property (rented our old townhome for 6 years before regrettably selling it), and would like to get to 5-6 of them, and this one would be relatively convienient since it is across the street.
For down payment, my in-laws have agreed to give us $100k towards the down payment. We might be able to pull other money together on this but I just want to base it off of bringing $100k to the deal. Was thinking of a 30 year mortgage. Would we need to put 25% down since it will be an investment?
Right now, I am not working with an agent. I have several friends that do it, but I'm not sure that I want to use any of them with the whole friend/business relationship. Our old neighbors already have an agent, as it is listed, would I be making a mistake of just using the same realtor? Would that save any money?

I'm open to any and all advice on this.

Thank you.