1) It's a hack, but you can do that by setting UndoDepth to the number of undo records - 1 and resetting it back to the original value. You will also need to count the records from an UndoActionRecorded event handler.

2) The TextStyle value is passed to the Drawtext API function and you can use any combination of flags supported by it. Note that DT_BOTTOM also requires DT_SINGLELINE, so setting bottom right alignment will look like DT_SINGLELINE + DT_BOTTOM + DT_RIGHT, i.e.

' bottom right alignment
box.TextStyle = 32 + 8 + 2

where the flag values are listed below:

#define DT_TOP			    0x00000000
#define DT_LEFT			   0x00000000
#define DT_CENTER			 0x00000001
#define DT_RIGHT			  0x00000002
#define DT_VCENTER			0x00000004
#define DT_BOTTOM			 0x00000008
#define DT_WORDBREAK		    0x00000010
#define DT_SINGLELINE		   0x00000020
#define DT_EXPANDTABS		   0x00000040
#define DT_TABSTOP			0x00000080
#define DT_NOCLIP			 0x00000100
#define DT_EXTERNALLEADING	    0x00000200
#define DT_CALCRECT		     0x00000400
#define DT_NOPREFIX		     0x00000800
#define DT_INTERNAL		     0x00001000 

I hope that helps,
Stoyan