Martin McAvoy and his parents

Dear IRO (Graignamanagh, Kilkenny),

Am searching for my great-grandfather Martin McAvoy, his parents and siblings.
He shows up for the first time on a marriage record in New Orleans, LA dated 14 Sep 1871.
His first wife, Margaret Murphy passed in 1879. He married Margaret's sister, Mary Ann Murphy,
my great grandmother, on 25 Jun 1881. I have a lot of documents pertaining to Martin from
1871 onward but nil prior to that year.

On most records from the New Orleans, LA,  Public Library and on the US Census of 1880
Martin indicates that he was born in Ireland in 1835 and that he arrived in USA in 1850.
His port of arrival is assumed to be New Orleans - although I could be convinced otherwise.
On his marriage license to Margaret, Martin states that his mother's name is Judith and his father's
name is Philip. (as an aside - Judith and Philip are also the names of two of his children.)

Searching the rootsireland.ie webisite I found (at no small expense) one Martin MacEvoy
with parents Philip MacEvoy and Johanna Doyle. This Martin was baptized on 14 Oct 1838
in Graignamanagh, Kilkenny. This is the only Martin MacEvoy in the 1835 time frame with
parents named Judith and Philip.

Searching other records in the rootsireland.ie website I found a parish marriage certificate
for Philip MacEvoy and Judith Doyle on 12 Feb 1822. This caused my heart to skip a few beats.
Further searches for Philip and Judith's offspring produced James MacEvoy (baptized 14 Jun 1828)
and Mary MacEvoy (baptized 19 Nov 1834).

Searching on Philip MacEvoy produced a baptismal record Philip McEvoy
in Clogerhead, Louth on 29 Apr 1798.
Philip's parents are listed as Pat McEvoy and Cathe Fitzpatrick. What's interesting about 
this record is that it lists one of the sponsor's as Peter Markey whose surname is identical
to the maiden name of Martin's future mother-in-law, Margaret Markey Murphy of Dunleer, Louth.
Could this Philip McEvoy be Martin's father?

Searches on Judith Doyle in Kilkenny produced two baptismal records:
Muckalee 1802 and St. Mary's, 1803.
Found one burial record for Judith MacEvoy in Ballymahon, Longwood, Meath on 19 Mar 1850.
... this would seem to tie with Martin's journey to the USA in 1850. Yes? 

Further - I found one P. McAvoy and an M. McAvoy arriving in New Orleans on 3 May 1854.
Ship's name was American Union and it embarked from Liverpool. Could be a red herring
given the later arrival date - but still worth tracking.

Questions:
1. What was the usual time between birth and baptism back in the day?
    (e.g. could Martin have been born in 1835 and baptized in 1838?)

2. Martin was a minor in 1850. Could he have traveled alone to the USA?

3. What became of Martin's father and siblings?
   Am finding no records of Philip's / Jame's burial nor travel.
   A Mary McAvoy Beattie (b. 1830, d. 1909) shows up in Wayne county Michigan.

Any help you can provide is greatly appreciated.

Willaim Tyree
Downers Grove, Illinois