GLPI 11 - Asset Definition and Custom fields improvement

In GLPI 11, I started to explore the integration in the core of Generic Objects and FIelds plugins, which is amazing. Some ideas to eventually improve the function:

1) If we create two new assets, let's say Asset A and Asset B, and we use Asset B as a mandatory dropdown type field for Asset B, I should not be allowed to delete any Asset B which is uset by some record in Asset A table. Is there any way to implement this kind of foreign key control?

2) Other than say a field is mandatory (not empty) or not when using Custom Fields, is it possible to implement some rules about Regular Expression the field has to meet?

3) I used to import data through thee GLPI Plugin "Data Injection". Is there any plan to make it part of the core, and so compatible with Custom Assets and fields?