Don't get to close, physically, with them and try not to have too much fun together.
It could mean your ex is trying for a friendship basis or, he may want to keep tabs on who you are dating (not uncommon.)
She doesn't want you to be upset with her or lose your friendship but also wants to be able to keep dating your ex. Sometimes others are more compatible than others and if this is your ex and truly your friendship then really think about things and decide if this really matters.
You don't. If you want to keep your friendship with your best friend then you should not date their ex. You will end up losing your best friend over a relationship that will most likely not even last long while you friendship can last a lifetime. SO don't screw up a friendship over a little relationship.
Keep talking to them keeping it at the friendship level. You might even buy a gift! He/she will be your friend in no time. But he/she will never stop being your ex in reality.
No, you should not do this
Simply because she doesn't want to lose you all together. She still wants that friendship and connection with you.
It will be difficult to maintain a relationship with your niece if the ex-wife has sole or primary custody and you end your friendship with her. Why not simply stay on good terms with her?
The hardest thing in friendship is to sustain it. You have to keep the same level of friendship all over.
Your ex-boyfriend may miss you, but you have to keep moving. Keep in mind there is always a reason why they are an ex.
He just means that he is happy that you are friends as he "values your friendship" - he enjoys your company and is glad you are friends.
Put yourself in your your husband/wife's shoes. Would you want him/her conversing to their ex fiances, ex lovers? I think it's more respectful to not converse. Don't do it.
Yes, Depending on your relationship/friendship with that person.