Re: bedtime - both my babies sort of 'chose' their bedtime themselves when they got to about three months old - they just started to get tired at around 8pm and then do a long sleep rather than a nap, so I went with it, and gradually brought it earlier as needed.
When my second child (now 7 months) was that age, she was going to bed after the toddler, so about 8.30ish (toddler in bed at 8). She would just come with us as I did my son's bedtime routine, but she wasn't generally crying I think and seemed to enjoy it (funny how quickly you forget!). She absolutely loves the bath so that helps. They had a bath together, with the baby in a bath seat, and then we'd all do a book together. I'd then leave her downstairs in my bedroom in a bouncy chair while I actually put my son into bed, which is quite a quick process. If she cried I left her to it, it was only a few mins. I found a dummy invaluable though if she did get grumpy, I'm not sure how I'd have coped without it!
Now, she goes to bed before my son - he's dropped his nap so goes to bed much earlier than previously, around 7.15, and now she's just on two naps a day, she's generally in bed by 6.45. He watches a bit of TV while I give her a bath and put her to bed (30 mins tops), then I bathe him and put him to bed. This is just what works for us - some people may find it easier to bathe them together. In due course I think I'll probably do them both together but I quite like a bit of individual time with both of them and it's calmer.
If she's crying for most of the routine, is she tired / hungry? If tired, could you try putting her to bed before the toddler, while they watch a bit of TV. If hungry, could you get in a feed somewhere eg during story to tide her over till bedtime? And if just wants cuddles a sling as suggested above could work. Maybe try a few different things and see what works best, then stick to it.