In answer to your questions:
What else do you need in the home apart from toys? I'm thinking of things needed for activity's (paint, paper, glitter & glue etc) and protective plastic perhaps for your floor, or has that gone by the by! - yep loads of crafty type stuff, things for water and sand play, dried food like rice/pasta for making pictures/musical instruments etc, 2 highchairs, travel cot, stair gate, step for access to loo and basin, cups, plates, cutlery, double buggy, correct car seats/boosters etc (As I say, I had most of this already, just bought an extra highchair from Ikea and an extra toddler sized car seat from Asda.)
Have you got outside play stuff too? I have a swing, slide, sandpit, ride on toys, bat and ball type games, footballs etc - again haven't bought anything as my children had loads anyway.
Is there a ratio for number of children v size of home? I am registered for 4 under 8's plus my own 2 so max of 6 altogether in a average sized 3 bed semi with garden. If you live in a smaller house, or a flat, your numbers may be reduced.
What is an average day like.....do you have to arrange back to back activities to keep them busy or is your day more relaxed with maybe one or two planned things and then see what happens...? No - I know my little ones favourite activities so often use those with additional bits to keep it interesting. We go to toddler group one morning per week regularly but the other days i can choose to take them to the zoo, the park, the library etc or just stay home and play in the garden or inside depending on the weather. When i have 4 after school, including my 2, another 4 yr year old and a 2 year old they all entertain each other beautifully....so far.....