Don’t worry about the chicks, as long as you have a place for them to hide they should be ok.
As for saddles, that depends on what you’re going to do. I use a general purpose ‘English’ saddle which I have had for 30 years - it’s a generic no name brand.
I would look online for a used one, already broke in. Ask the person if you can borrow it to ensure it fits the pony.
You can go online and check out how to ensure the saddle fits. You also want it to fit you, an average size is 16” seat. That is what my saddle is and I am very petite.
Make darn sure the billet straps are in good condition, those are the straps you attach the girth to. Again if you go online you can check out these things.
And stirrup leathers need to be also in good condition. I can tell you one day I was riding Lulu in the bush galloping down a sandy lane when my right stirrup leather broke. I almost fell off - luckily Lulu stopped when she felt me shift from the stirrup giving way. Bad Kelly! They were cheap leather I bought them because they were cheap - and they broke easily. I went and bought a good set of leathers.
I use both a leather girth and a string girth. Ask your friend what she uses when she rides him.
As for bridles a plain snaffle will likely do fine. I use a full cheek snaffle as a regular ring one can be easily pulled through the side of their mouth if you try to turn and pull too hard on the reins.
And for a saddle blanket get something easily washed - cotton is great. Make sure you wash that regularly in hot weather. Which you get lots of! Dry it in the sun after every ride.
