1. Without further information (and without qualification to practice law in a second jurisdiction) I cannot say for sure what happens the foreign property, but if it were an Irish property, the matter would hinge upon whether the co-ownership was as joint tenants (in which case it passes to the surviving owner) or tenants in common (in which case the deceased's interest in the property goes to the named beneficiaries in the will, or if there is no will dealing with this asset, to the next of kin - in this case your husband).
2. Foreign bank accounts - should pass to person named in will as beneficiary (unless the will excludes dealing with foreign assets - see below).
3. "If there was a second will abroad, which one takes precedence?" depends on wording and date of the two wills. The "standard" wording for an Irish will states that it revokes all previous wills, but that might not be the case here.
Some general observations:
A. For clients with foreign assets, I believe that the best procedure is to make jurisdiction-specific wills. In other words, if a man has property in Ireland and Spain, his Irish will should expressly state that it deals with all his assets excluding the Spanish ones, which are (or are to be) the subject of a separate Spanish will.
B. There are laws in Ireland which limit the ways in which you can dispose of your estate (for example you cannot totally disinherit a spouse). Other jurisdictions have similar rules - it is important to be aware of them.
C. A "common law" husband does not have any automatic succession rights in Ireland.
D. It is often the case that an executor is also a beneficiary. This may feel a little like a potential conflict (and sometimes it can operate that way too). But unless there is some reason to suspect duress or undue influence in having had a particular person named as executor, I think that the choice of executor should carry a lot of weight, and should be respected.
It would seem fair to guess that the option of naming her partner as executor must at least have been considered by the deceased. She apparently decided that she wanted her brother to look after her affairs. Presumably she knew her brother fairly well and had a fair good idea of how he would deal with people. I think that in these cases people are a little to quick to forget that in dealing with the executor, they are dealing with somebody chosen and appointed by the deceased. To disagree with the choice of executor is to disagree with the deceased. I hope that when I am dead my next of kin will respect my decision on this issue.
One final comment, (and as I really don't know anything about the individual circumstances here, it is certainly not directed as a criticism - but if it is applicable please take it as an attempt at impartial and constructive observation). When drawing up wills, I will frequently go into far more detail than the clients feel necessary. Time and time again, I have clients say "ah sure they will work it out between themselves" to which I always respond that it is not their children I am concerned about, but all of their husbands and wives. On division of estates, the silliest disputes break out over the most minor items, and it is more often than not the case (in my experience) that the influence of in-laws rarely operates in a calming way. Tread carefully. Your marriage is far more important than a few pesetas, and these situations have a way of breeding lingering resentments.