1:Fairly harmless and easy to achieve, however you have a Wife, assuming you do by your wanting a threesome, probably not a good idea to pursue unless of course she likes the idea.
2:Said this before i’ll say it again, research research and research again. As well as positives there are a lot of negatives to this. Although the idea may sound fun the reality can sometimes be completely different.
3:As with No.2
4:Best you start playing with Anal toys! Well in advance.
Most of all, you should really start off by mentioning some of them to your partner just to see how she reacts/feels.