First you may want to talk to the IRS custodian for more clairty...
1) What does it mean? I opened traditional IRA long time ago, but did not contribute too much money there. If you made deductible and non deductible contributions to ANY traditional IRA then you cannot just convert the non deductible part by itself.
2) Hard to understand. In general, roth contribution is after tax money (non deductible), while tradition IRA contribution is before tax money (contribution should be deductible for some people). This is a correct statement.
3) What do you mean shortly? If I made the traditional contribution years ago and money sitting there for years, can I transfer $10k to Roth IRA ($10k of backdoor roth conversion)? Do you mean you have had an IRA for several years with no earnings ? You cannot convert ONLY the deductible contributions ... the conversion would be a % of the earnings, deductible and non deductible contributions.
4) There is no way to make partial conversion? And leave some asset in traditional IRA? You can convert any amount you wish each year from just $1 to the entire IRA balance however you cannot ONLY convert the non deductible contributions ... the form 8606 is used to compute the taxable portion of the conversion.
