I wrote a plugin for my lossless audio compressor La for foober2000 version 0.5. However, with the new version 0.6 I discover the plugin needs to be updated. With regards to this I have two questions:

1. Will it be neccessary to update plugins with every new minor release? I might note here that if this is the case I will reconsider supporting foobar as such a situation is hardly workable.

2. I tried to simply recompile the plugin with the new SDK, however received a number of link errors. Just wondering if anyone can hint whether this is normal or whether I've simply screwed up somewhere. I was hoping that there wouldn't be any changes neccessary to the plugin code.

RTFM

usually all you need to do is to recompile with new sdk without any sourcecode changes (at least for input plugins), and this happens only every major release.

1. I think it's slowly getting more stable. You have to consider the fact that foobar is still a beta.

2. There were some pretty big changes to the SDK (which is why the version number was bumped). Most of them were good changes, which make the logic cleaner (e.g. metadb_handles are now used many places playlist_entries were used previously). You're almost certainly going to have to make some changes to your code, though. 0.6b14 was a pretty big change.

I guess the question is - how often/frequently/much is it expected to change? Could anyone perhaps give a vague estimate? Would help me in deciding whether I should wait for version 1.0 or something or rather try and keep up-to-date with each new version.

component compatibility will be broken next time there is a reason to do so, probably about 0.7. like i said above, "converting" components to new version of foobar2000 usually requires the same sourcecode to be recompiled with new SDK, possibly with a few changes (i don't remember any changes in input API between 0.5 and 0.6 that would actually require sourcecode to be modified).
if you are having problems compiling, then release your sourcecode and we will keep compiling for new versions instead.

There was one change that affected also input components, name sample format. If you don't do anything exotic in foo_la you only need to change sample type from 'float' to 'audio_sample' and recompile.

foo_la most likely decodes to fixed-point PCM and uses proper helper classes, so it's not affected at all by that change