You get paid for keeping in touch days so I'd doubt very much you'd be able to take baby in..... I guess every employer is different to some extent, buy my understanding is that even if you only go in for 1 hour (team meeting, for example) then that is one of your keeping in touch days used, or you go in for the whole day. However your employer will only pay you for how many hours you do. Other than that I'm not that clued up yet as my lo is only 3 months so trying to not think about it just yet!
It depends on your HR policy. At my company you are absolutely not expected to spend the whole day. Usually 1-3 hours. Sometimes with baby but without if you can. Regardless you get paid for the whole day.
Check with you HR policy. At my company you are not expected to be able to find childcare as you are on mat leave however it makes the kit day more valuable if you can as then you can do trying etc. There was never any pressure on me to not bring baby though.
I plan to use mine, but quite close to my return to work date. It's completely up to me whether I'm only in for a few hours or a whole day, but I will only be paid for the actual hours worked (but would still count as one of the 10 days). It's not usual practice at my workplace to bring the baby, it wouldn't be appropriate.
My plan is to save them for the end of maternity leave, when I'll be on unpaid leave, to get the maximum out of the pay! Here I get paid for the whole day, no matter how long I'm in for, but it depends on your employer's policies.
My employer pays for the whole day, even if just an hour is worked. I wouldn't normally count something as a KiT day if the employee brought the baby in but this probably depends on what type of work it is.
Where I work if you're still being paid enhanced mat leave pay then you won't be paid for KIT days so it would only be financially beneficial to do them after 6 months. I've never heard of anyone coming in to do one with their baby though.