A basement conversion is not the easiest thing to achieve. If the work is done particularly poorly, the results can be really disappointing. However, if an experienced team of builders is used then the outcome should be exactly what you wished for. This is because they will have all the skills necessary to translate your vision into reality.
You should get your builders to have a look at your plans and your existing basement. They will have the ability to assess the extent to which the foundations will support the work. You will benefit from the fact that they will have had the opportunity to reflect on issues like headroom, so having a dialogue about your plans is a great way of making practical progress.
You might think that you should try to get the building team to concentrate on the issue of damp prevention. Luckily, an experienced group of workers will be thinking about it before you do. It is really important that a basement conversion does not suffer from this problem. In some instances, a plastic membrane can be added to a basement to limit the potential impact of damp, so this is the way forward whatever the specific purposes that you have in mind for your basement.
In some cases, planning permission may be required for your project to be implemented. It makes sense for you to discuss this with your builders; they should be aware of whether or not the planned conversion does necessitate any action. This may be in part because local knowledge can be of considerable value in this context.
Even if you work out that planning permission is not essential for your scheme, building regulations will apply. You should not be at all intimidated by this point. Your builders will have the capacity to look at relevant issues such as ventilation and wiring.