HELOC or cash for primary residence/investment duplex

[Samuel Metcalf]

I'm all over the place on this one with a mix and match conundrum.

I've got a duplex that's been awesome for me. It's got a $200K mortgage on it with a value of... at least $325K. Best case $400K. I've been eyeing up buying a second investment property: my partner's parents' place. They've been great owners, keeping the upkeep strong, and lately putting about $40K into it to ready it for sale. My guess is they'll ask about $250K. I believe I'll need about $50K for closing, right? With 20% being the common minimum expected if it's purchased for an investment?

Then there's our primary residence. We bought a new build last year and it came with a lot to be desired on the landscaping end. We're ramping up efforts to improve that this spring/summer. I'm just guessing here... maybe $40-60K in improvements?

We have $50K in cash. Another $50K in savings that we'd like to leave untouched. 

Is there an obvious answer for what's the better move to finance either the landscaping and home improvement projects? Cash should go to the purchase? The landscaping? Vice versa the HELOC? Does it matter? Appreciate any and all opinion.