prior year building on Section 179

[Kea]

New client came in for me to do their 2006 and 2006 tax returns. She brought me the 2001-2005 returns. (2001-2004 were prepared in Sept 2005.)

There is no depreciation or Section 179 taken for 2001-4. There are items listed as "other" on page 2 of 2003 Sch C that appear to be assets:

Trailer $1721

Portable Office $2053

Storage Unit $1976

For 2005 Schedule C "other", they listed:

bid plans / septic plans $2277 (this is OK?)

Septic tank - construction $18,602

And (my favorite) took section 179 for Mobile home office $34,013.

For the assets shown on the 2005 return, I can just file an amended return since the accounting method has not been used for 2 years - right? (06 has not yet been filed.)

The 2003 changes would require a Form 3115 - right?

What is the impact if the client decides not to make these changes? I'm sure they won't be eager to pay many thousands of $$. Although, she did ask me to review the old returns for mistakes.

Thanks for your help.