You have an interesting case, and there are some options in how to work.
First: When you implement a new ERP system, you will have to change the way you work. You will be better off with adapting how Odoo works, than modify the process. But, you can add functions in order to be more effective. E.ex. a smart button on the sales order to get short cut to the BOM availability report.
The it depends on your total business process from Quotation->Sales->Delivery. A big difference would be if you use MTO or not. General recommendation is to avoid MTO.
Without MTO best pratice is to set up replenishment rules on components, and perhaps also on finish goods. Setting min / max quantity. There are two options to follow up: Let Odoo automatic create Purchase RFQ and manufacturing orders with the automatic Scheduler, or use the function: Inventory->Operations->Replenishment.
Alternative components: You can have more than one BOM on a product. You can change at the manufacturing order before it is confirmed. I am a little in doubt of how to use it, but you can set a sequence and a default one, and change on the manufcaturing order. If there is a lot of alternatives, this might be a headache to administer. You can also change components direct on a manufacturing order before it is confirmed.
Alternative vendors: Register the vendor on the product in tab Purchase. It will be created/updated automatic from purchase orders also. You can move the default on to top of the list.
Since you have a lot of components, I imagine also there are several work places. If som consider to set it up as multilevel. Multilevel is when you create a semifinished product that is a component in the next order. A general rule in manufacturing is that: If you have several work stattion / work centers and products are placed on the shop floor between, define that product as a semifinished som you have stock and availability
