Hi everyone! I'm new here and I really need as much help as I can get.

I have my own little shop and it started as a made-to-order / customized cake shop but due to clients' suggestion I have decided to offer ready-made cakes as well. The problem is for made-to-order / customized cakes I usually let my client decide which type of icing they prefer (flavor, color, etc...) and bake the cakes only 1-2 days before decorating it (except for fondant)

Now I understand that it will be totally different for 'ready-made' cakes. From what I had been reading it seems like buttercream would be the best option for me to use as it has a longer life that other types of icing. Is that right or is there another type I can use?

The buttercream recipe I am looking to use for these cakes is the wilton recipe of part butter part lard which I know will last longer. So mainly my questions are:

1) Which type of frosting should I use?

2) How long will an iced cake using 'that' specific frosting will last?

3) In what temperature should I keep the cakes?

4) Are there other ways to make the cakes last longer?

Hopefully you guys can help me. Though I have been doing customized / themed cakes for a long time I have not really done cakes commercially. Any suggestion is greatly appreciated. Thanks in advance!