Replacing old garden beds

Hey guys I’m 23 and just got a new property this place has been neglected for a while and I’m trying to get the old garden beds up and running again I have only done landscaping for 1 year when I was 18 so knowledge isn’t the greatest although I do have a few questions

Can I reuse old irrigation lines (some are cracked is it hard to connect up new lines onto the old or should I replace the lot?

Where’s the best place to get the wood/ sleepers beams because Bunnings is quite expensive

The soil seems to hold a bit too much moisture as it doesn’t get full day sun due to the trees that overhangs so when I get new soil should I add perlite to the soil mix to get better drainage or is there a better option

I’m trying to make it properly but I am only renting so I don’t want to dump thousands into it but any tips are appreciated cheers there are 4 beds that are 4.5m X 1.5m and 1 that’s 1.2m X 1.2m