Well done you!
Ok, well you will have other leaders helping you so you can delegate!
Don't worry about your qualification, you will do it all just by running the unit really, there will be some training sessions to go on but most are valuable anyway. You will be able to attend trainings where you basically spend the day making different things and trying out ideas and you;ll come home with a whole load of new activities to do.
Rainbows don't camp but can go on sleepovers. You will need an additional qualification for that. Don't worry about it yet, baby steps!
The meeting itself will be an hour to an hour and a quarter ish. Rainbows have different badges they can do called roundabouts. To do a roudabout you do several different activities based on a theme. We used to do one a year and base a whole term around the theme. There are also other badges that all ages can do with a variety of themes and activities that can be adapted to the age group. The leaders will have access to all those resources, most areas have communal copies of things like that. YOu also get challange badges and things coming out all the time, often based around a specific event or written bya team going abroad who sell the badges to raise money and write activities you can get your girls to do to earn the badge.
Planning time varies, it gets easier the longer you do it! Crafts can take a long time to plan as you have to prepare templates etc, the key is to keep it simple so they can do most of it themselves. Generally in one meeting you will do warm up games perhaps based on the theme of the night, an activity (craft, baking, sciencey) and then perhaps a follow on activity to take it deeper or a fun game or a bit of a sing song befor ehome. Obviously everyone does diffferent things but I'd say that is pretty common as a set up.
On top of that you have accounts. Accounts need to be kept and checked and signed off yearly. There is a specific spreadsheet written for it. You don't have to use it but it is very good. So long as you enter all new income or expense as soon as you get home rom the meeting then it shouldn't go wrong and shouldn't take any time.
Guiding does tend to take over your life, but in a good and enjoyable way. Running a unit isn't too bad in terms of time really but if you get more involved. Weekend things, fundraisers, fairs, helping out with something else, more training then you can spend a lot of time doing it!