Harry, to answer your questions:1) If you intend to continue your self-employment then you are eligible for a Solo 401k plan.2) You can rollover your IRA into Solo 401k, regardless of the balance.

Here's a resource for ESOP basics, distribution and rollover rules:https://www.nceo.org/articles/esop-participant-dis...Depending on how you take distributions, you could build up your retirement accounts over time and invest in REI through those accounts as well as outside.

They also told me - if you see one you like you have to jump on it immediately (that marketing ploy of "sense of urgency".Thank goodness my 401K rollover took longer than I expected - I haven't been sent a listing email for over a month.  

@Bj Ayoleke, unless you have a few hundred thousand dollars in your account it probably makes the most sense to roll over funds into the 401k at your new job and then borrow against from the 401k for a down payment on a property.  

Rick, a Self-directed IRA is an Individual Retirement Account (any individual with earned income or funds to rollover can have one).

A Rollover is  also possible but definitely try to do the transfer.

Following are the similarities and differences between the solo 401k and the self-directed IRA.The Self-Directed IRA and Solo 401k SimilaritiesBoth were created by congress for individuals to save for retirement;Both may be invested in alternative investments such as real estate, precious metals tax liens, promissory notes, private company shares, and stocks and mutual funds, to name a few;Both allow for Roth contributions;Both are subject to prohibited transaction rules;Both are subject to federal taxes at time of distribution;Both allow for checkbook control for placing alternative investments;Both may be invested in annuities;Both are protected from creditors;Both allow for nondeductible contributions; andBoth are prohibited from investing in assets listed under I.R.C. 408(m).In order to open a solo 401k, self-employment, whether on a part-time or full-time basis, is required;To open a self-directed IRA, self-employment income is not required;In order to gain IRA checkbook control over the self-directed IRA funds, a limited liability company (checkbook IRA);must be utilized;The solo 401k allows for checkbook control from the onset;The solo 401k allows for personal loan known as a solo 401k loan;It is prohibited to borrow from your IRA;The Solo 401k may be invested in life insurance;The self-directed IRA may not be invested in life insurance;The solo 401k allow for high contribution amounts (for 2017, the solo 401k contribution limit is $54,000, whereas the self-directed IRA contribution limit is $5,500);The solo 401k business owner can serve as trustee of the solo 401k;The self-directed IRA participant/owner may not serve as trustee or custodian of her IRA; instead, a trust company or bank institution is required;When distributions commence from the solo 401k a mandatory 20% of federal taxes must be withheld from each distribution and submitted electronically to the IRS by the 15th of the month following the date of each distribution;Rollovers and/or transfers from IRAs or qualified plans (e.g., former employer 401k) to a solo 401k are not reported on Form 5498, but rather on Form 5500-EZ, but only if the air market value of the solo 401k exceeds $250K as of the end of the plan year (generally 12/31);When funds are rolled over or transferred from an IRA or 401k to a self-directed IRA, the amount deposited into the self-directed IRA is reported on Form 5498 by the receiving self-directed IRA custodian by May of the year following the rollover/transfer.Rollovers (provided the 60 day rollover window is satisfied) from an IRA to a Solo 401k or self-directed IRA are reported on lines 15a and 15b of Form 1040;Pre-tax IRA contributions on reported on line 32 of Form 1040;Pre-tax solo 401k contributions are reported on line 28 of Form 1040;Roth solo 401k funds are subject to RMDs;A Roth 401k may be transferred to a Roth IRA (Note that from a planning perspective, it may be advantageous to transfer Roth Solo 401k funds to a Roth IRA before turning age 70 ½ in order to escape the Roth RMD requirement applicable to Roth 401k contributions including Roth Solo 401k contributions and earnings.)

However you can roll over to a solo 401k or a self directed IRA.

Once I retire, I will have control over an IRAP (IRA as part of a union pension plan) and a 401K.I have spoken to the union's plans administrator, and he says that I will be free to roll over both accounts as soon as my retirement is finalized. 

I do have ~$500k in a traditional IRA I could rollover to an SDIRA and use - regulations permitting.