"from the county Leitrim," (U4.126)

This is an 1890 map, showing the counties of Ireland. Milly is in Mullingar, Co. Westmeath. Bloom is going to Ennis, Co. Clare, for the anniversary of his father's death. Clongowes Woods is in Co. Kildare. Belfast is across Co. Antrim and Co. Down.
"Then, lo and behold, they blossom out as Adam Findlaters" (U4.127)

Alex. Findlater & Co. had several branches in Dublin, and sold Teas, Wines and Whiskies. Daniel Tallon was Lord Mayor of Dublin 1898 - 1900.
A bill from Findlater (1911) listing their many branches. Ross Hotel had purchased from them bottles of JJ&S for 4s 7p.
"or Dan Tallons." (U4.128)
"Then think of the competition. General thirst. Good puzzle would be cross Dublin without passing a pub. Save it they can't. Off the drunks perhaps. Put down three and carry five. What is that, a bob here and there, dribs and drabs. On the wholesale orders perhaps. Doing a double shuffle with the town travellers. Square it with the boss and we'll split the job, see?" (U4.128)
"Then think of the competition. General thirst. Good puzzle would be cross Dublin without passing a pub." (U4.128)

Indeed it is possible to cross Dublin without passing a pub, as published on the web June 14 2011
Image ⓒ OSM Contributors CC-BY-SA
"How much would that tot to off the porter in the month? Say ten barrels of stuff. Say he got ten per cent off. Or more. Fifteen. He passed Saint Joseph's National school. Brats' clamour. Windows open. Fresh air helps memory. Or a lilt. Ahbeesee defeegee kelomen opeecue rustyouvee doubleyou. Boys are they? Yes. Inishturk, Inishark. Inishboffin. At their joggerfry. Mine. Slieve Bloom." (U4.134)

This PC shows an Edwardian boy's classroom.
"He halted before Dlugacz's window, staring at the hanks of sausages, polonies, black and white. Fifteen multiplied by. The figures whitened in his mind, unsolved: displeased, he let them fade." (U4.140)

Not Dlugacz's, but a same era Beef and Pork Butcher shop. Notice the sausages in the window.
"The shiny links packed with forcemeat fed his gaze and he breathed in tranquilly the lukewarm breath of cooked spicy pigs' blood." (U12.142)
"A kidney oozed bloodgouts on the willowpatterned dish: the last. He stood by the nextdoor girl at the counter. Would she buy it too, calling the items from a slip in her hand? Chapped: washing soda. And a pound and a half of Denny's sausages." (U4.145)

The Willow Pattern, or Blue Willow, is a distinctive and elaborate pattern used on ceramic kitchen & housewares. It was designed by an English engraver at the Caughley porcelain factory (most likely Thomas Minton or Thomas Turner) c. 1780, in the 'chinoiserie' style. The landscape typically has, at the center of the composition, a willow tree and two flying doves; on the right a large building with an ornate roof; on the left a smaller building, a variety of trees, and a bridge with human figures; in the foreground a zigzag fence. This is a Willow Pattern bread plate from Wicklow, Ireland.
"His eyes rested on her vigorous hips. Woods his name is. Wonder what he does. Wife is oldish. New blood." (U4.148)
"No followers allowed. Strong pair of arms. Whacking a carpet on the clothesline. She does whack it, by George. The way her crooked skirt swings at each whack." (U4.149)
"The ferreteyed porkbutcher folded the sausages he had snipped off with blotchy fingers, sausagepink. Sound meat there: like a stallfed heifer.
He took up a page from the pile of cut sheets:" (U4.152)
"the model farm at Kinnereth" (U4.154)
"on the lakeshore of Tiberias. Can become ideal winter sanatorium." (U4.154)
A SV (1900) of Life on the shore of Galilee, at Tiberias.