Teachers can give students lifts if they are with another member of staff, it doesn't happen often but it can and the rules are just that it has to be 2 members of staff. Emoji reactions cam be on emails too, they are on outlook etc, just saying it's not always social media. Yes happens more with 6th form etc, and female teachers have more leeway, but you can heart a kids email, if it's funny or whatever or it's just them thanking you.
Different schools have different policies, most of the time it's just use judgement, avoid touching but teachers can read social situations, and if a kid is genuinely crying or something, and they hug them, if the student wants that, nothing will happen. Yes be open, but i think teachers can use situational judgement, some schools may have no touching as a rule, even if students are fine with it but some don't. On leavers day etc if a kid is close with a teacher they'll hug them, leave cards etc. You can be professional with judgement and still have friendly emails, nothing wrong with saying your proud of them or will miss them etc obviously some SLTs will set different tones etc, some heads hug students, they are sensible with situations. Well in schools I have had experience eith these are the policies, I know some have different ones which I personally think are OTT, but if within the school OP's children go to those rules work then, then those are their rules.