You are buying a crop sensor body and Canon uses 1.6 APS-C sensors. The focal lengths are based on a 35 mm camera so with a smaller, 1.6 sensor the zoom range changes as followed:
10-20 is like a 16-32
18-55 is like a 29-88
24-70 is like a 38-112
55-250 is like a 88-400
70-300 is like a 112 - 480
For landscape photography, a wide angle zoom would be good. 18-55mm is a often the kit lens and when you have to buy it seperately, its not expensive. Just try and use it at lens openings from 6.3 - 11 where it is at its best. A 50mm prime (a 1.8 is really cheap) would have higher quality because there are fewer glass elements involved. This would be the equivalent of an 80 mm lens and is good for portraits. You do cover that with an 18-55mm lens or a 24-70mm lens, which would be even better for portraits (Tamron has a 24-75mm F2.8 with a macro function). A 70-300mm is not so easy to use without image stabiliser unless you have plenty of light or use it on a tripod. A macro function on a lens is even better on a prime, like a 100mm lens, but you could also use a cheap prime with rings to get good macro shots. Reverse mounting can give good results. Here is a link for cheap solutions for macro:
A Poor Man's Guide to Budget Macro Photography - Envato Tuts+ Photo & Video Article. Here's another link:
5 Cheap Alternatives to a Macro Lens and another one:
How to Enjoy Macro Photography on the Cheap (use Google to read up on other macro solutions). Really, the choice of lenses all depends on the photography that you thing you are going to do a lot. Because you said that you were looking for portrait and general scenery + architecture, I would recommend a wide-angle zoom, combined with a prime (maybe with extension tubes or reversing ring for macro?). For lens reviews, I can recommend
dpreview
Here is also a prime crop conversion with the 1.6 crop on the right:
8mm = 12.8mm
10mm = 16mm
14mm = 22.4mm
17mm = 27.2mm
20mm = 32mm
28mm = 44.8mm
35mm = 56mm
50mm = 80mm
85mm = 136mm
105mm = 168mm
135mm = 216mm
200mm = 320mm
400mm = 640mm
500mm = 800mm
600mm = 960mm