Why is a Full Database Backup (as opposed to a level 0 backup) required in Oracle after switching to ARCHIVELOG mode

There are lot of things I would like to say

What I'm looking for is some suggestions or 'gotchas' that may arise from switching some to the FULL recovery model.

As far as I know if you change recovery model of database during maintenance window time or when load is relatively less there wont be any problem. It wont create a situation.

I'm also aware that as soon as we switch to FULL recovery that I need to run a full backup on that database. (I understand that FULL mode won't be truly enabled until we do this).

You can take differential backup also perhaps this would be very helpful if you have big database. anything that links LSN chains would do.See below link it has good information about switching between recovery models

http://msdn.microsoft.com/en-gb/library/ms189272.aspx

My plan is also to weekly run a full backup, wipe the log files from the previous week and, essentially 'start over'.

Stop there, this is not correct approach just because you did a full backup and log backup please don't be in idea that you can safely remove old log files and full backup. Do you have a plan to test old backup by restoring to actually see that in case of disaster this backup files would work. Remember only successful restore guarantees that your backup is totally consistent. Do you have a option to check backup integrity.If not please include it into your backup plan. At least keep 4 day old backup files( this is what I do on local disk) before if you delete backups This strategy is upto you keep backups for time where you are sure they wont be useless if disaster strikes. Sometimes business want only specific data change to which was made couple of days. I also have my database backup up on tape and that tape is stored for 6 months.

(maybe switch to BULK_LOGGED for that time period as to not explode the log file?)

Changing recovery model to bulk logged and doing bulk logged operation would make you loose point in time(PIT) recovery so if you are concerned about PIT recovery dont do that. Instead rebuild index through intelligent script which only rebuild fragmented index like one Is Ola Hallengren index rebuild solution please note that if Index is rebuild with full scan for that index stats is already updated with rebuild process.

If you do heavy DML please break it into batches so as not to explode log files.

A partly online backup is certainly possible but switching to and back from archivelog mode needs downtime. As an alternative you could run in regular archivelog mode and trash the generated archived log files, until you run a backup.

For the backup to be recoverable it is important that it has ALL archived log files that were generated during the backup. End the backup with a log switch and also include those archives in the backup.

You must see this kind of backup as partially online. It does allow you to restore to the point in time where the backup completed, not to any other point in time. Very similar to regular offline backups, only, taken online. It saves downtime.

Why do you want this? This is a lot of effort just to safe maybe 10G of archive storage per day. It also introduces an extra error source and many dba's won't be able to work with this and expect to have all archives. My advice would be to keep it regular online backups, with regular archived log backups and keep things simple.