Some general questions

[Alexander Kant]

1. I have red here then when I have in table1 3 fields like:
id INT(10),
name VARCHAR(30),
description TEXT

and want to find some entries, in this big table, I should split this into two tables, table1:
id INT(10),
name VARCHAR(30),

table2:
description TEXT

Why should I do it for statement like: SELECT * FROM table1 WHERE name = 'alex'
Why should be this faster? MySQL have to search for alex first in column name - and then give the result back, with a description.

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2. When I have to tables and following statement:
SELECT t1.*
FROM t1
JOIN t2 ON t1.id = t2.id
WHERE t2.name = 'alex'

is this a better way?:

SELECT t1.*
FROM t1, t2
WHERE t1.id = t2.id
AND t2.name = 'alex'

and what is about this one:

SELECT *
FROM t1,
(SELECT id
FROM t2
WHERE name = 'alex') tmp_table
WHERE t1.id = tmp_table.id

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3. I have one table with 10000000 companies. My search-engine have to find all companies in new-york, there are (axample) 500000 companies. Now I have to display 10 companies only, ordered by! name - or by postalcode or something else.
I know that order by is problematic - with performance. But before MySQL can give me my 10 companies, it have to sort 500000 compienies? right?
Are there a good solution to solve this problem?

Regards,
Alex