My DDog was spayed recently and I was very too.when we collected her, she was very drowsy and I had to carry her in from the car, but she became more alert over the next couple of hours. We kept her in her crate for the first day and tbh she didnt really want to be anywhere else - shecwas very quiet and subdued for a couple of days. We just took her out to the garden on her lead every couple of hours, for toileting.
We used a medisuit, rather than a buster collar, for the first ten days, which worked very well and she seemed to barely notice it. You have to remember to undo the end (poppers, like a babygro) when you take her out to wee. One time I forgot 
. Its useful to have two bodysuits - wash one, wear one. You must undo it every day to check the wound for redness, pus etc.
We were given a liquid solution of painkillers to give each day. My dog wasn't very keen on it, so we had to mix it in with her favourite food to make sure she ate it - chicken and rice, scrambled egg etc is good to tempt the palate.
We were told to keep to short, on-lead walks for the first ten days, which we did. She was fine with this for the first five days or so, but after this she was desperate to go on longer, off-lead walks, and got quite bouncy at home. We stuck to the rules but she didn't like it!
I would say she seemed back to normal after about five days post op, but we still had to be careful until ten days post op. Three months on, there is no discernible personality change - although I have been told that her coat is likely to become more woolly over the next year or two.
Good luck!