Not much intermarriage at all. Each has its own separate identity and pride is high. Ireland had very few Romany until the EU grew to include Eastern Europe, when Roma groups began arriving in large numbers. There are a lot of New Age folk but afaik they're mainly to be found in the west, and have possibly moved to greener pastures since the economic fizz died in Ireland.
The attempts by the Irish government to settle the Travellers began in earnest in the 1960s - the miserable sites which are now home to a lot of Travellers on the outskirts of cities are a reflection of the failure of those old policies of past decades, a failure which was due to the reluctance of Traveller men to be domesticated plus the Nimbyism of all but the poorest and most voiceless of settled communities.
Those communities deeply resented the presence of Travellers, fully realising what it meant in terms of their own status. Further, the communities tended to be brand new council housing tracts which had virtually no amenities for anyone, no established bus routes, schools in pre-fabs, no playgrounds, no nearby shops or doctors' offices, no local police stations. Support for young families, whether settled or Travellers, was not available.
Most are now very blighted communities and urban planners have devoted mush effort to remedying the problems (demolition and redevelopment of Ballymun for example.) In Galway, redevelopment of a squalid housing complex which had been home to both Travellers and other very poor families included input from residents and a say in how the community was to be run. In NI, Travellers were treated with outright hostility by Loyalist gangs who saw them not just as Travellers, but Irish and Catholic.
The settlement efforts included 'serviced' sites (concrete slabs for the caravans and running water available at a communal spigot, walls around the sites, and gates) and concrete block tigeens, all for small groups, as well as allocation of council houses to certain families. Initially the tigeens were often burned in the spring as the families got ready to resume travelling for the summer. Truancy officers and HVs could visit - which some Travellers found annoying. Generally speaking, the sites didn't work out very well, and the fate of families housed in the poorest areas wasn't much better.