Creating a more than 4 primary partitions

Before you do anything, do a full metal backup as things do go wrong with these types of processes.

The "easy button" is Acronis Disk Director for $24.

The other way to do this is by editing your partition table.

NOTE: This procedure doesn't work (I don't think) on a system (like a Mac) that uses EFI.

To do that, boot off a linux live CD and run:

sudo sfdisk -d /dev/sda > partitions.txt

...in a folder you can write to. That will give you a file called partitions.txt that has your partition table. Then edit that file using your favorite text editor, and put your logical partition above your extended partition by changing the numbers and order.

For example, if your sda5 is the partition you want to make primary, change "sda5" to "sda1" (or 2/3/4) and push the rest of the numbers down. The main point is you want to make sure the start, size, and id are the same.

Then run:

sudo sfdisk --force /dev/sda < partitions.txt

In answer to your second question: while you can resize partitions, you cannot move them. The start of a filesystem cannot be changed. So if you want to add 10 GiB after drive C: D:, you'll need to delete drive D: C: and recreate it in the proper location. Second, you should delete your extended partition sda2 and recreate it to fill the remainder of the space. Otherwise, you'll be restricted by the boundary at the end of sda2; you can't make a partition cross that border.

Also... if the check keeps failing, it may point to a bad disk.