There are several signs of affection, and this answer will assume you are asking this in terms of human affection between men and women. Typical signs of affection include hugging, stroking, soft brushing of skin (i.e. Brushing your hand against someone's arm or face when talking, kissing, holding hands, putting arms around each other. These are just some of the more obvious signs of affection between men and women, and quite often friends, especially girls. Other subtle signs of affection can include prolonged eye contact either when speaking to you or just looking at you (sometimes called gazing), smiling and playing/fiddling with hair is another common sign of affection shown by girls who are shy around guys they like. Girls tend to be more openly affectionate towards other girl friends in contrast to guys with their other male friends; for example, a girl will often hug their friends closely and for a prolonged time, whereas a guy will usually do a firm handshake, or a 'man hug', which is a more manly and firm version, usually involving patting of the back, with less time together. The top halves of their bodies will touch momentarily amidst manly patting, but the bottom half will hardly touch at all as many men find this uncomfortable. On the contrary, girls will often have no problem with full body contact during hugging friends and loved ones, as they are typically more open to affection than many men. This is only a generalised outlook though, and obviously there are exceptions to the rule.
Yes they could all be said to be signs. Another way to tell if a person is attracted to you is their pupils will enlarge (dilate) when looking at you. This is something we generally only notice subconciously, and is why dark eyes are instinctively attractive to us, because it is a sign the other is receptive to us.
When he bends down for no reason in the middle of a grocery aisle to kiss my forehead.
Holding hands is a sign of affection, the other things you have mentioned are censored I can't explain loll
Holding hands in public , A couple showing public displays of affection
Those you have mentioned are all signs and it sounds like you are smitten, good luck