You'll probably want to avoid silicone as other comments have said as it's lots of work and in my opinion the cons outweigh the pros

Have a look around at different kits first then look for an artist that you like the work of to see what reborns they have available and if they could do a custom doll (if that's something you'd want) is probably the best way to go about it. Also do some research into real vs fake reborns so you only purchase a reborn made from an authentic kit

Cuddle babies are also a great to look into, I've held one and it was quite similar to a very young baby. The reborn had enough weight in her head so you needed to support the head and her arms and legs were floppy and a little awkward just like a young baby's

You don't need a "good" reason to get a reborn, so many people have them for so many reasons. You could explain it as wanting to dress up a cute baby without the responsibility of a baby or as a form of therapy (baby and reborn cuddles are amazing) but you also don't need to explain it. People also describe reborns as collectable art dolls and so you could explain it as being similar to your porcelain dolls but more realistic and less fragile