I owned it 30 days later and it took me a year to finish all the repairs.

Duplex or triplexes all day to start.

Probably correlated with being attracted to a career consisting of sitting alone in a room and staring at numbers all day. 

You may need to hire a property management company to handle day-to-day operations, which can eat into your profits.

If not we could work out a down payment with cash, and finance the repairs through our day jobs. 

We are interested in making use of the STR tax strategy to offset our W2 income this year (work 100+ hours, average rental less than 7 days, no one else worked more than us).But1) Can we only keep it as short-term rental for 2024 collecting minimal STR rents and convert it to LTR in the following year (2025).

I'm very knowledgeable but for the past 3 years I've spent all my time being a full time day trader.

Second as mentioned you probably would have to move out the day before and find a new tenant right away to avoid the appearance of buying a primary home. 

I am currently a Sales rep that drives long hours during the day from customer to customer.

Rent paragraph typically spells out the revenue share - that's another blog of its own but generally speaking it is a percentage of the gross collections identified in various equations of percentage of revenue or some percentage over a minimum base amount per machine per day.