Hi
I have a budgie.
First please pleas never have a door or window open when they are flying free. They will get out they are very inquisitive.
Budgies can make great but demanding pets. Then can require a surprising amount of attention.
2 are better than one if you want to be less hands on as they will bond with each other. They can still be tamed and allowed to fly round but it will be slightly more tricky.
If you want to train it to talk you would be best with a male bird kept alone. But then you will have to give him a lot of attention as he will need you to be his flock. Several hours a day out if cage time with you.
The poo...is easy to clean up and very small but they poo a lot. I'm talking every 10 minutes. And moult feathers and drop seed everywhere. They are messy buggers. And they chew everything. Wallpaper,letters, phone cases, any food you leave lying around, paintwork and furniture.
But they are so sweet and can be very affectionate and loving. You. An teach them to talk, to give kisses, to fly to you when you call - all sorts.
I would recommend the budgie forum talk budgies. Just google it. There is so much advice on there about behaviour,diet and training.
Diet wise a pellet based diet is best but a lot of them won't eat it or have to be persuaded as they don't view the pellets as food. My budgie and I have reached a standoff in this respect. They like green salad items and most veg as well as fruit (well supposedly but mine is having none of it)
Don't feed people food it's bad for them. Only veg/fruit. Mine has a nibble it a cracker or crisp from time to time but he really shouldn't. He goes mad for them when I'm eating them though 
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Does that help ?