If you'll excuse the slight delay in replying:
- In 1.(F)/100 Holert replaced Hptm. Hattan who took up Holert's old post as SK of 1.(F)/33.
- Holert was due to fly down and join his new command in Biblis on 7 February 1945, although the General der Aufklärungsflieger's KTB does not record his appointment until the 26th for some reason.
- Holert was alive and leading 1.(F)/100 on 16 April 1945.
- Carlein was certainly an Ar 234 pilot with the Staffel but I don't know if he had temporary command at any time.
I'm working on an article about 1.(F)/100 and the Ar 234, probably for my website, so keep a look out for it.