Moving to UK - tax and investment questions

Moving to London to work for UK company. 

UK company provides a 3% match for a pension scheme.  Can I take advantage of this money some day if I end up retiring back in the US?  Any ideas on the specifics of how it would work?  What if I just move back to the US prior to retirement, can I withdraw that pension money?

My current 401K in the US, I intend to roll over to a traditional IRA  and contribute to it yearly from whatever I save in the UK.  Does this make sense?

Finally, my UK salary will be more than USD $80K.  Will I have to pay US taxes on the amound over 80k ?

Thanks

In general, you can collect on UK pensions when you are resident in the US.  You should confirm if there are any specific aspects to your plan that might prohibit this, such as minimum work requirements.

As for what method to use to withdraw the money, wait until closer to the day, about two years or so before you move.  Because tax laws and treaties may change many times between then and now, and advice you receive this year regarding your pension withdrawals will not be accurate by the time you retire.

Your plan to rollover your 401k into your IRA will not result in any additional taxes in the US or the UK, so that's okay.  Your plan to contribute to the IRA may be a flawed one.  You have many pension contribution options:  additional UK contributions as well as US ones, and the treaty affects these.  Invoking the contribution clause of the treaty may be optional in the US, and has major consequences in the year of your retirement.  I would suggest you seek some advice regarding the treaty implications before contributing to any plan.

You can take a Foreign Tax Credit for the UK taxes due on the income in excess of $80,000.  Your US tax is thus likely to be zero.