If I convert a disk from basic to dynamic is it possible to format it to master boot record (MBR) or is it just possible to format with GPT?
There are two entirely orthogonal dimensions here:
Thus, the MBR or GPT configuration of a disk exists "underneath" its configuration as "basic" vs. "dynamic." In setting up a disk, you normally select MBR vs. GPT and then select "basic" vs. "dynamic" -- although in practice, an OS installer may make both these decisions for you, and may not even tell you what decisions it's making.
Unfortunately, the Windows partitioning software has a tendency to convert "basic" disks to an LDM/dynamic configuration without warning. This can wreak havoc if you're multi-booting or sharing a removable disk with another OS. If you run into this problem, you can use tools like EaseUS Partition Master to convert back to a "basic" (plain MBR or GPT) setup.
Most tools can convert MBR to GPT or vice-versa only by completely deleting all the partitions on the disk. IIRC, EaseUS can do so losslessly. So can my GPT fdisk (