question: can your Irish contributory pension be affected negatively by receipt of UK pension? and if so how?
As someone else said, the only negative may be tax.
But at retirement age, with an income tax exemption limit of 18k a year (36k if married), the full Irish pension on it's own is around 12,650 so even with your 'small' UK pension on top of that, you may not reach that limit anyway unless you have other income.
State pensions are exempt from USC.
Normally, if you are entitled to pensions from various EU countries you are meant to apply in your country of residence and the local social security agency will apply to the other countries.
Normally yes, but I don't think this rule is particularly strict or enforced because the retirement age in Ireland is 66, but in the UK it's 65, so I'm guessing that's why the OP applied direct to the UK one year ago, rather than going through the Irish system one year early.
In your case, the UK should take into account your social insurance payments in Ireland when they calculate your entitlements. If you applied independently,they will not have known about your payments in Ireland. It may be that they would not have any effect but ...
I don't believe that would make any difference to the OP.
The UK would only need to take into account his Irish PRSI record if he didn't meet the minimum 10 years contributions needed for a standalone UK pension.
If he had less than 10 years contributions in the UK, for example 4 years, then yes, the UK would take into account his Irish (EU) record, and pay him a pro-rota UK pension of 4/35.
But as his standalone record in each state entitles him to a portion of each state pension independently, the UK will pay his UK record based entitlement , and Ireland will pay his Irish record based entitlement.