I'm not an expert in this area, but in relation to your queries above, perhaps you can explore the following points with your pension trustee:
Would the beneficiary (my spouse) receive all the assets from SSAP intact via the estate or is it true that the assets have to be liquidated to cash first?
1. With a SSAP, if you were to die tomorrow, the trustee would have to liquidate the assets to pay out the benefits - I know Gordon has said otherwise but check this point with your trustee. If the assets were in a PRSA, I think there is a mechanism in the Pensions Act for the assets to be conveyed to the personal representatives of the estate. But, the PRSA is not as advantageous to you right now as your SSAP.
2. You don't say in your post if any of your SSAP assets are a transfer from a previous pension arrangement. If so, the transfer value will be available for payout as a lump sum and does not have to go towards an annuity. Again, it is an area that is ripe for maladministration so if there is a transfer value in there, make sure your records reflect it accurately so that it gets paid out as a lump sum and not used to purchase an annuity.
Is purchase of an annuity an absolute requirement?
3. Hopefully, you'll be around long enough that you'll be collecting your cheque from the President on reaching 100 years of age! If you were to pass away tomorrow, the SSAP will be limited to paying out 4 times your Final Remuneration + any transfer value as a lump sum, with any excess going towards an annuity. If you have had some high earning years (as it looks like the case from the numbers you quote), I would make sure that this information is available in your records to your spouse and the trustee, especially if you have had some earnings in the form of fluctuating emoluments. As Gordon has said, Final Remuneration can be the basis for the payout of the lump sum on death in service and not just 4x salary. This is often an area that can get maladministered so you want to make sure the trustees pay out the maximum amount that they can as a lump sum and limit any compulsory annuitization.
4. As the poster above has mentioned, 'preservation' is a very useful part of estate planning. Probably not much use though if you get hit by a bus tomorrow as I presume you want the SSAP and the 'relevant employment' that it is tied to to continue. But, if you were in a position whereby you had a terminal diagnosis and had time to plan, this would have to be part of the plan.
5. I would not worry too much about the above. You are young. I think there will be a lot of changes in the pensions area in the not too distant future. The recently published Report of the Interdepartmental Pensions Reform & Taxation Group recommended in item #22 in their table of conclusions that: "as an alternative to compulsory annuitization, the ARF option should be available for excess funds remaining after the payment of the maximum death-in-service lump sum." If this becomes policy, this would allay your fears around the annuity and your estate could benefit from an ARF.