Sure but I don't think from "you should do X to stay safe" comes "you are morally obligated to do X".

Often times when people are intimate, they just go with the flow. Kiss each others necks, grope each other. Two people arent making out and then ask "may I kiss your neck". They just go for it if they sense the passion and urgency from the other person. It's often times instinctual.

To an extent possibly, but you should try and obtain some form of consent before genitalia get involved. If I was snogging someone and they grabbed my dick, I would be a bit shocked.

They may rub your thighs and if you dont push their hand away or stop them, they will proceed to go for the middle. Maybe for the sex part they may say "lets find somewhere private' or "lets take it to the bedroom' something in that vein, but they may not, and just go with the flow.

I mean you definitely need to obtain explicit consent to go from kissing to full on sex.