Please accept my blessings. I am in due receipt of your letter undated and have noted the contents. The answers to your questions are as follows:
1. For the portraits of Gaura Kisora and Jagannatha das Babaji, yes you can use the mangalarcana prayers, and also the same for Bhaktivinode Thakura.
2. You can sign your paintings with your personal names.
3. Regarding Devahuti's painting for Ādi lila, yes you can use it. I think it is nice. You can also use the painting you had suggested previously. Both can be used.
4. Yes, it is understood that your paintings are offered to the Deities when they appear in books or on the temple walls. It is understood like that.
5. Regarding asking me questions, yes you can ask, but unless it is sanctioned by me, you cannot act on it.
I hope this meets you well.