I really, really wouldn't worry about bad habits. Not napping properly is a far worse habit to get into than needing to nap on someone (I speak from experience of both!) If she'll drop off some other way, just keep trying that occasionally.
The way babies can go to sleep does change too. My DS would never reliably sleep in the pushchair (half the time he'd yell and fall asleep eventually, half the time he'd just scream and keep screaming - and stay awake). But at 11 months all of a sudden he started dropping off really quickly and easily (without tears) in the pushchair, which has continued since.
I think babies are different in when they're ready to nap in a cot. DS did it from 14 weeks, but I'd rock/feed him to sleep, then put him down. I still put him down asleep now (16 months) but if I pushed it, I could probably have persuaded him to go to sleep on his own, but both he and I enjoy the cuddles too much for the time being.
I always fed DS often, including before and after every sleep, as well as any time he asked for it, so I never classed feeds as 'full' or 'top-up' type ones.
If you feed to sleep & she wakes when you put her down, then feeding her in bed is a good suggestion.
There are some suggestions for helping babies adjust to sleeping in a cot in the No-Cry Nap Solution by Elizabeth Pantley (she calls it the 'Pantley Dance').
It does get easier after 3 months too. Up till then, babies go straight into 'active' REM-type sleep for the first 15 minutes or so, which means they wake really easily. After about 3 months they go straight into a deeper sleep, so it's much easier to put them down.
HTH