Hello Bex and welcome
Whilst I personally wouldn't say that ALL persistent texters are timewasters (ie people with no intention of booking, turning up and paying the correct fee), I think it's fair to say that if you're relatively new and therefore shining like a beacon to every numpty within a hundred miles, that you may as well assume so. The two examples you've described are typical - basically they are getting to engage with you in some way for free, which is what they want and anybody asking for things like more pictures/videos, trying to bulldoze in offering you things you don't want or need or wanting you to go into any sort of graphic detail about services (aka what you will 'do to him' during a booking) are guaranteed no-hopers.
Genuine punters aren't interested in messing about - they want to book and get to do real things with you in real life and have better things to do; they'll ring or email with a good idea of when they want to book and how long for, and if they want anything specific they'll know how to ask questions politely and using adult language (ie 'I see you offer anal, is that extra or included in the fee?' and suchlike rather than ' do you take it up the arse?'. If you see what I mean.
The exceptions to the too-much-texting rule I've encountered have tended to be rookie punters who are a bag of nerves and honestly don't know how bad they're making themselves look (they tend to send lots of texts just to say 'hi' or 'looking forward to seeing you later' and so on); all you need to do there is tell them that you're glad they're excited, but their booking's all sorted and they don't need to contact you unless there's a change of plan. If it keeps up after that, see above.