depending on his behaviour, he may, once he is there, be subject to a DOLS order. That wont stop you taking him out, but will stop him going out on his own.
They may well be able to reason with him over toileting issue, and better manage his nutrition
its hard, but might be the best thing that could happen for you both, No, you probably wont get choices of placement- first and foremost it needs to meet his needs . You say he can be aggressive at times- that needs managing and may not be manageable in many places